AT&T now charges $5 for a SIM swap. Not the end of the world but more free money for them. Guess it is one of the downsides of T-MOBILE as they charge so why not the others I suppose.
The agent said it was to compensate AT&T for the reps time.
Did a quick chat with AT&T and the agent confirmed this change just came about 2 days ago and even via chat they have to charge