Not sure what's going here. But Teams will try to use the domain-joined account whenever possible. There are a few things to check and keep in mind. Have a look at the computer account settings (if Mac have those) to see if there are multiple accounts added there. Make sure to be signed into Outlook desktop client with the same account as Teams desktop client. Verify that you're signed into the correct organization from the top right corner in Teams (the tenant/org switcher).

You can remove all info in the Teams cache location in your Mac. Navigate to ~/Library/Application Support/Microsoft. Right-click the Teams folder then select Move to Trash.