Microsoft teams for online lectures sounds like something which might require an enforced modification of browser policies, but in many cases the message is intended for average users who do not join any 'teams', and don't like a 'team' manipulating their browser.
"Managed by Your Organization is a Google Chrome feature which, if enabled, can be seen on browser’s menu along with ‘This Device is Managed by Your Organization‘ line. By default, this feature was provided in order for network administrators to set browser usage policies for users within organization. However, regular home users can suddenly notice this warning as well and not surprisingly, it can seem slightly suspicious, especially when it prevents the user from changing certain browser’s settings."
https://geeksadvice.com/remove-chrome-managed-by-your-organization-browser-hijacker/
"If you are a part of some organization, then your administrator can apply various settings/policies which is OK. However, when you are not a part of any organization and see such a message on your personal computer, it might irritate you. But there is nothing to worry about. Thankfully, there is a built-in feature in Windows 10 that can help you get rid of this message for Firefox as well as Edge browser."
https://www.thewindowsclub.com/your-browser-is-managed-by-your-organization-says-firefox-edge