I'm on MacOS, not Windows, but I really concur with you on the notifications. They're huge, they stay on screen too long, and they can't be dismissed early. I hate that they chose not to go with the standard MacOS notification system.

Another MacOS annoyance: Teams seems to exist in every virtual desktop, so even if the main window is in (say) desktop 3 and I'm in desktop 2, if I cmd-tab to Teams it won't take me to desktop 3. I have to manually switch desktops to get back to Teams.