See What Teams an Account is a Member Of

Microsoft Teams has its own Powerhell Module. Please see the article on connecting to Azure/Office365.

Once connect to Microsoft Teams, you have a few options:

See all Teams:

get-teams

See all Teams a user is a member of:

get-teams -user This email address is being protected from spambots. You need JavaScript enabled to view it.

NOTES:
https://docs.microsoft.com/en-us/powershell/module/teams/?view=teams-ps