But at the same time, do they still hide/mask/minimize review comments when there are more than 10 in a row?

That is the worst with their UX currently, only challenged by the stupidity of the code diff page that hide the most modified files so you can easily miss them and it is impossible to do a ctrl+f search on the page.

Amen. I lose comments and get confused as to why merging is blocked on a regular basis.

Scrap the entire PR experience, start again from basics. Fire the people responsible.