Comment # 1 on bug 1221734 from Takashi Iwai

You should be still able to use the old Leap 15.4 kernel on your Leap 15.5
system.  Could you try to install the old Leap 15.4 kernel and identify which
kernel version started showing the problem?  The Leap 15.4 (update) packages
should be available at
  http://download.opensuse.org/update/leap/15.4/sle/

And, if you figure out the working / non-working kernel versions, please give
the dmesg outputs from both (with debugging options) to compare.