Here, on my daughters Laptop, a Lenovo s540 with Intel integrated graphics,
there is the same Problem with 5.4 kernel. I still had the 5.3 around in the boot menues,
so the sound works with the old kernel.
No configurations have been inappropriately touched!
The PC is intensely used for remote schooling due Covid-19,
so no debugging is possible at the moment.
Thanks!
gnasch