Please take a look at video comparison between 2.8.2 and 3.2.1 where I quickly bash chords:
Both apps have “open in low-resolution” ticked in Finder properties and have identical settings.
3.2.1 simply fails to register notes. UI feels less responsive in general as well.
I’ve tried everything: low- and high-dpi modes, auto/manual scaling, fps limits on/off, windowed/maximised/fullscreen mode.
Plugin shown is AU 64bit, but instrument doesn’t matter, sample based instruments behave the same way.
Note that 2.8.2 is also laggy when “open in low-resolution” is not ticked.
My machine is MacBook Pro 15" 2018.