My Kubuntu updated from kernel 5.4.0-42 to kernel 5.4.0-47 and my laptop's keyboard stops working (except brightness keys). Booting back to 5.4.0-42 solved the problem.
Keyboard also works perfectly on Windows 10 (I have dual boot).
Keyboard also works in GRUB (2.04). But it does not in kernels 5.4.0-47 and above.
Updating to Kubuntu 20.10 (beta) does not help either (kernel 5.8.0-20 same problem).
My problem is similar to this one: Keyboard on HP notebook stops working under kernel 5.4.0-45-generic
And yes, I've seen this on launchpad: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1894017
So what's the problem and why is it not fixed in whole range of kernels 5.4.0-47 – 5.8.0-20?