It feels like a quarter of the time screenshare doesn't even work in Teams and it's noticably choppier when it does work.

Code blocks working in Teams is inconsistent, and it seems to add additional spaces when copying.

Quoting & mentions also sucks. The channels, chats, activity screens are always a mess, feel like UX bandaid.

Private channel limits are garbage.

Search and discovery sucks.

There's inconsistent options for the calendar between Outlook & Teams. Don't you dare expect functional compatibility between MS products. Scheduling assistant sucks, sometimes confuses itself when people are busy.

The UX seems to rely on a myriad of nested menus & modals that are XHR backed, so each one lags. Even just typing text feels slow. It's as fluid as molasses.