The latest version of Sonic Mania, 1.06.0503, which finally has Denuvo removed, also makes the AMD bug worse.
We have a regression on our hands, folks.
Although Denuvo is no longer mucking around, consuming CPU, etc., this latest version makes the old INI setting "shaderSupport=n" ineffective. The FMVs are always in color regardless. Regardless.
Absolutely no way to achieve perfect point sampling with AMD, anymore.
(And I tried AMD's custom resolution feature and GPU scaling with image centering. It works, accept vsync enabled in this configuration slows the game to a crawl. Seems like a GPU scaling driver bug. Might as well bite the bullet and stretch to 16:9, at this point.)
Sonic Mania on Switch has an audio bug where there is crackling/harshness/distortion. This is most easily heard in high sounds like rings and the cash register sounds at the end of levels and special stages.
This seems affect all audio in the game. This is probably related to poor (audible) sample rate conversion. Does not happen on Xbox One.
one solution i could see out of this is to adjust the volume of certain sounds just like what you have outlined there so the "crackling" doesn't become too obvious. otherwise all issues are on them.