We are a SMB experiencing the same (very frustrating) issue.
Any time someone logs onto a computer, Teams gets installed under their profile. When users don't log on for a while, Teams client gets stale/outdated. Our network vulnerability scanner picks up on this and shows Teams as being outdated...for every user profile on every computer that has not been logged onto for a while.
Forgive me if I haven't explained the situation well but...I'm very verklempt. It is stunningly unbelievable that Microsoft handles Teams this way. If anyone has a fix for this that does not involve GPO or scripting (shouldn't have to do either of those things to address this incredibly annoying Microsoft-caused issue), please let me know.