Thankfully I haven't used teams for a while, but my main issue with it was that it was trying to do everything poorly rather than one thing well. It's text chat, video chat, file storage, it had every MS Office product integrated. That meant you had to force your way past a bloated mess to get to the function you needed. The video chat was lacking the options that zoom had. It didn't have a proper speaker mode at that point, it used phone audio rather than speaker audio, there were less good options for screen sharing(whiteboards ect). It was always slow, memory hungry, buggy and unstable on Firefox/Linux. The desktop app was no better because it's literally just the web app in electron, but it had the added problem of being very difficult to fully close.

Very glad to be rid of teams.