Additional features, settings, or issues not covered by specific Microsoft Teams categories
Agreed! Unable to have multiple windows of the app bites.
Workaround... Open MS Teams in browser (https://teams.microsoft.com) and duplicate the tab. Can move the tab onto a separate monitor. If have the app open too, will have three instances of MS Teams (i.e. one of the app; two in the browser).
Limitation... When opening more than two tabs, even if move the tab to a separate monitor, you do get an annoying notice that says, 'are you still there?', but you can click on 'I'm back' and it keeps you where you were originally.
Cheers!