There is a window to opt out of the change, but if you don't expect to pay more for a new plan.
T-Mobile Is Forcibly Moving Those on Older Plans to Some of Its Newer Ones in November. Key takeaway: You can Opt-out but have to call T-Mobile Customer Care to do so. My Magenta to Go5G basic plan would cost $240 more annually for the added additional bonus of...extra hotspot data. That's it.