In earlier builds I think 9.1/9.2 early beta builds ( I can not remember that far back, sorry yes I do have a certified memory problem due to a brain in jury ???? WTF this word is a real world word and needed in the name A.B.I aka Aquired Brain In jury SORT YOUR CENSOR BOT out & learn to use the English language correctly " YES I am Brittish" and ,mi speling is carp as wel ) my 4gig pi4 had temp issues while "doing nothing just sitting idle" The temp was always over 50 deg c untill a fix was found and in the 9.2.1 build idle temp dropped a good 5 deg c to hover about the 45 deg c mark and I only heard the fans kick in every now and again while it was in playback .
I updated to 9.2.3 to see if it might help with the menu tearing problems and a problem I have playing a 4k file that gets to a certain point and trashes / reboots the pi. I should report it but I think it is a corrupt file and not really bothered about the film so I never got round to it.. Back to the main problem the idle temps seem to be back up to 50 deg c + again and the fans kick in whilst I am watching normal tv with the pi just sitting idle. The pi is on 24/7 so anyone in the household can flick to the " rpi device" and watch whatever no matter what time of day they are up, I know I could just nudge the activation temp up a bit but It was running at 45c before on 9.2.1 but after the upgrade to 9.2.3 its idle is 50c +
Nothing else was added or removed software wise only the upgrade to 9.2.3 and firmware / usb firmware updated to latest versions (2020-04-16 & 000137ad)