Hang on… I’m a Teams admin at my work, and I can see data about individual people’s calls, whom they’ve called, and for how long, as well as connection telemetry. I can, however, not see chat messages unless I add myself as an owner of every Teams channel. I can definitely not see peer-to-peer chats. I’m pretty sure this isn’t even possible in Microsoft Teams Admin Center.

I think what you’re referring to is Microsoft Purview, which is a premium toolset that can be used to, among other things, extract chat conversations in case of legal investigations &c. Teams in itself does not have any spy functionality, to my knowledge.