I had something similar in my landscape materials & it was due to some clamping issues. So, values got beyond 0 or whatever.
Maybe some other stuff used that material does not with the newer versions of they have changed a bit.
Maybe you can go into the material itself & find where this is coming from. You might need to disable some nodes & find the culprit manually.
I’m subscribing to this thread to see how you fixed this issue or get some tips from others.