Hi tomera69 - as a Gen11 TigerLake user - it didn't work until a mid release kernel 5.11 - a challenge playing catchup on hardware versus software. Intel generally do a good job in having the software ready. But there have been a large number of updates into the kernel mainline in the last 12 months. The LibreELEC 10 kernel (5.10.x - was released 2020-12-13) The Linux Kernel Archives - Releases which is why the 2021 CPU is not "fully supported / has issues" - we keep our LibreELEC nightlies up to date - we currently have 5.16.5 in place (Released 1st Feb 2022) - linux: update to 5.16.y by heitbaum · Pull Request #6141 · LibreELEC/LibreELEC.tv (github.com) - which should support ALL available shipping Intel CPUs.
>> There are usually several "longterm maintenance" kernel releases provided for the purposes of backporting bugfixes for older kernel trees. Only important bugfixes are applied to such kernels and they don't usually see very frequent releases, especially for older trees. <<
Here is a diagram showing how mainline kernel development occurs. As you can see features are NOT backported to a Long Term Support (LTS) kernel. And given that the CPU would be after the LTS 5.10 kernel was released - the support may / may not be in the 5.10 kernel.