Teams has added the ability for moderation of channel conversations. If you moderate a channel, only team owners can post new conversations and you can restrict things even further by stopping members, bots, and connectors posting. It’s a feature that helps to control communication in channels intended to publish and share information.
The tabs in a Teams channel can be associated with many different forms of data. When you delete a channel, you only remove the conversations for that channel. Any other data is left intact, including files in the folder in the SharePoint site used by the team. To fully clean up a deleted channel, you must therefore check what tabs exist and what data is accessed through those tabs.