Regarding to DVB-T2 only - I am using 2 kinds of Astrometa DVB-T/T2 USB stick (with Panasonic MN88473 and Sony CXD2837ER demodulators) and also MyGica T230C DVB-T/T2 USB stick (with Silicon Labs Si2168 demodulator), currently with LE 11 Nightly on RPi 4B and all working fine as they are supported yet by Linux (MyGica has a better sensitivity, Astrometa has more features / more possible use cases for a lower price).
I am not using any DVB-S2 receiver.
OK, thank you both! 
Currently I am going to upgrade LE 11 Nightly 20211005 on another boot media (USB stick) to 20211015 to test if I fell to the same issue or not. I'll put a result here. I could also try a fresh installation later but I believe it will work at first attempt.
I think my configuration is a bit specific - I am using Live TV / PVR with Astrometa DVB-T2 stick, also the i2c LCD display so some add-ons are also more or less a bit specific. Maybe that's why? Some add-on incompatible with fresh Kodi which couldn't be upgraded automatically without the advancedsettings.xml?
Edit - upgrade another LE 11 from 20211005 to 20211015 stopped with new Kodi picture on screen after the bottom line, informing about add-ons migration, disappeared. Kodi log ends with Waiting message (about 25 minutes ago):
I'll try to reboot to see what happens afterwards.
Edit 2 - after reboot Kodi started without issue and Live TV is working.
Perhaps the original issue could be due the fact when LE 11 Nightly 20211007 was released, add-ons were not compiled yet so the add-on migration did not finish properly and it prevented Kodi from further starts?
Thanks a lot, you made it!!! My LE 11 Nightly is working again.
After updating advancedsettings.xml in accordance with your advice & reboot, Kodi started and displayed announcment that there's no PVR installed. I have confirmed it, then Kodi's GUI appeared and some add-ons were updated automatically. Then Live TV started succesfully and everything seems to be working fine again.
Thanks a lot for your help, mglae !
Thanks for an advice, created the file and this is the fresh crashlog:
The same issue with LE 11 Nightly 20211014 and 20211015.
Found a thread discussing the error hdmi-audio-codec hdmi-audio-codec.1.auto: ASoC: error at snd_soc_dai_startup on i2s-hifi: -19
that I am experiencing as well: https://github.com/raspberrypi/linux/issues/4575
Tried to edit config.txt and cmdline.txt as outlined there but without any positive effect.
cat cmdline.txt
boot=LABEL=System disk=LABEL=Storage quiet video=HDMI-A-1:D
Thanks a lot, that's exactly what I was looking for - how to enable debug logs from console.
The fresh logs after update to most recent LE 11 Nightly 20211013:
You don't mention which kind of wireless communication is your Logitech keyboard/mouse using. If it has a proprietary USB stick, try to connect it through an USB extension cable (I know you wish to eliminate cables everywhere, but at least for test) so the stick will be far from RPi / external HDD. And test if it's better. I can imagine that such devices, using a very low power wireless protocol, can be sensitive to high-frequency noise that some devices / components may be producing. Also I would try to replace a battery in your kbd with a fresh one.
Shortly - if your LE on RPi 4B works with wired USB keyboard (and I am sure any mentioned LE package works), it's not a software issue but more likely a wireless device's issue, in combination with some hardware used. Of course if only REW and FF keys are NOT working properly and all other keys works fine, I may be completely wrong... 
It's not necessary to use a noisy fan. Yes the passive cooling would be the best option but in this case you always need a massive heat sink and still there should be an air flow around.
For one of my RPis 4B I am using as a compromise a smaller heat sink + 12 V CPU fan (60x60x10mm, used but a quality grade), powered by 5V from USB port. I's enough to have a reduced rotation speed so there's no noise and the cooling is very good.
I can sort of see where you're coming from but how is going down that route any better than continuing to use a wireless keyboard and having a separate remote for the TV?
OK, sorry I did not get your use case properly (as the very first post did not point out the wireless keyboard is the only control device you are using). I thought your issue could be related to HDMI CEC & TV Remote Control through which you are sending FF & REW commands to LibreELEC. As you mentioned Argon One case which is well designed for using IR Remote Control, I supposed the outlined solution could be suitable for you. I don't use keyboard with LE, from my point of view it's not necessary with properly customized IR Remote Control (yes I have REW and FF buttons there). I am sure I could use your Panasonic TV remote with LE without any issue.
But if your wireless keyboard functionality depends on attached devices, it's possible there's a HW issue which you need to discover. It could be even a noise generated by external HDD which breaks wireless transfers etc... Hard to say.
Are you sure argonremote.zip was created for LibreELEC? Most likely it supports only Python 2.x but LE 10 is already using Python 3 which is not backward compatible. So you should ask vendor for updating the installation scripts to be working with Python 3.
I would say it will need some manual configuration but it will work for sure on LE 10.
Look here: Kodi, Harmony, and Raspberry PI 4 with IR sensor newb guide
Focus on Setup points 10. - 11. Edit the key mapping file in accordance with your Remote Control.
Understood... You are welcome.
Edit - just FYI - 20211012: http://ix.io/3BA2
I have upgraded LE 11 Nightly from 20211005 to 20211007 but Kodi could not start afterwards. Then I tried to reinstall (by putting the image file to .update folder & reboot) with LE 11 Nightly 20211006 with the same result. Even reinstalling with (previously working) 20211005 did not fix the issue. Yestarday I tried to reinstall with 20211010, Kodi also does not start. After several attempts to start Kodi the LE reboots in Safe mode.
Does anybody know how could I easily make it working again please (hopefully I won't need to revert to a bit older LE release & restore configuration from backup)?
As there's no HDMI CEC standard in fact and usually it's a nightmare to make it working stable & reliably, I would recommend to configure IR Remote Control on LibreELEC to be independent of your TV.
Look here for more information (you don't need Harmony, any IR RC should be suitable, even the same you are using for your TV - just configure the key mapping accordingly).
My LE 11 Nightly crashed after upgrade from 20211005 to 20211007 - Kodi was not able to start, then LE rebooted to recovery mode. Reinstall to 20211005 did not help, Kodi did not start anymore so some files were damaged. Did not have time to analyze the issue / recover from earlier backup yet.
Edit - just tried upgrading to LE Nightly 20211010 but Kodi does not start on my RPi 4B / 2GB.
Edit2 - as it is a bit off-topic here, I am going to create another thread.
The nightmare is that you do accept OOM situations.
I know, you are right but it's only temporary... 
For research reasons a core dump is generated by default if possible. This can be disabled by
Code echo 0 >/proc/sys/vm/oom_dump_tasks
Great, thanks a lot! That's exactly what I needed to know.
that is basically too much
try 2500/800, that should work more reliable
Thank you, I have already reduced those values a bit and started monitoring free RAM online by script. It looks that latest LE releases are a slightly bit more hungry regarding to RAM as I did not have OOM issues with the mentioned settings couple weeks ago.
I believe the thread can be marked as Resolved.
Thank you for feedback / advice.
Yes I can try to decrease a Timeshift Maximum RAM size parameter a bit (currently 3090 MB on RPi 4B/4GB, running Tvheadend 4.2 and 1100 MB on RPi 4B/2GB).
But why the hell the LE is now freezing and generates a huge disk / SD card activity for several minutes when OOM killer is activated?!?
It did not happen in older LE releases (if OOM killer terminated Tvheadend, it was restarted immediately, the Timeshift data were lost but LE was not completely hanged for long time).
So it looks this behaviour was started on in some recent kernel version and it's a nightmare (and also not very good for SD card if there are writes).
Another freeze encountered on RPi 4B / 4G, running LE 11 Nightly 20211002.
As the issue happens too often and it's very annoying, I am afraid I'll have to revert to some earlier LE version as the stability is one of the most important features to me...
If someone have an idea how to prevent LE from freezing even though OOM killer is activated (like before), please let me know. Perhaps I should uncomment the Storage=auto option in /etc/systemd/journald.conf or set it to volatile?
