Got annoyed with Teams taking forever to upload a simple file.
Found that clearing Teams Cache would help and here are the steps to do so in Mac
1] Quit Teams
2] Go to Finder and get to ~/Library/Application Support/Microsoft
3] Delete the folder Teams from there
4] Go to Keychain Access App and search for Microsoft Teams and delete the entry.
5] Restart Teams
Credit goes to: https://www.uvm.edu/it/kb/article/clearing-teams-cache/