(1) I've not noticed any slowdown at all on page loading in Edge, Firefox, Chrome, Opera or UR browser for Pro 3.2.1
(2) It appears to blank out the Google Ads box on a lot of pages when using Dark Mode.
(1) On some browsers' addon pages, I see a lot of comments about not knowing the cost of Pro (which is $9.00 p.a./ 2c per day). That should be headline, not something you have to seek out.
(2) On Gmail, the options after opening an email disappear. Not a big problem - just right click and 'back' arrow.