One issue I have had several times is Microsoft Teams not updating its cache very well. This is most noticable to me when someone adds or updates a profile picture but Teams does not show it. To solve this specific problem I have resorted to clearing the cache manually. Depending on your operating system, there are slightly different steps but the principle is the same:
%APPDATA%\Microsoft\Teams\Cache and delete all the filesYou can navigate to that folder and delete all the files with Windows Explorer or Windows Terminal, whichever you prefer. The Environment Variable %APPDATA% is a shortcut to C:\Users\xxxxx\AppData\Roaming\Microsoft\Teams\Cache where "xxxxx" is your username.
rm -Rf ~/Library/Application\ Support/Microsoft/Teams/Cache/You could do the file deleting in Finder, but I find it more fiddly to get to that folder than the simple copy & paste on Windows.