> Downgrades are not supported, did you re-install? Yes, full reinstall over a wiped hard disk.
> Try the kernel from backports, currently 5.4. That was exactly the problem I had. Current kernels 5.4.x both on Testing and Sid produce constant GPU hangs on my Intel HD Graphics 530, The ones that outputs "i915: Resetting rcs0 for hang on rcs0" (https://bugzilla.kernel.org/show_bug.cgi?id=205545). It is supposed to be solved on 5.4.x but it is still present. So... no current Debian kernel is bug free and works needs to be done. This is the real problem.
