T-Mobile is arguably the carrier with the most reliable 5G service in the US, but like all other carriers, it occasionally does pretty questionable things. The carrier wanted to force some users on cheaper plans onto more expensive packages, and if they wanted to stick to their cheaper plan, they had to opt out manually. Evidently, since this news broke (especially since T-Mobile didn't announce it publicly), it got a lot of unwanted negative attention. So much so, in fact, that the company is backing out from its plans completely.
T-Mobile Backs Out of Forced Plan Migrations
No need to worry now.