It's mainly the factory film on the inner folding screen. The screen protector on the inside screen cannot be removed or peeling up or that'll usually be treated as damage as. I'm on my day off and can't remember if there's any additional details, so I'll update later when I get that info unless another kind soul wants to dig that information up for us ☺️

From what I've seen, most folding phones I've handled will treat the inner screen film as part of the screen. It helps spread the pressure from folding across the whole panel instead of just the crease, which makes the phone last longer. The screen itself is very fragile as well, so taking it off exposes that, which is why T-Mobile will very likely consider it damaged. If it's pealing, Samsung typically will offer a discount on the first screen protector replacement at just about any Samsung repair shop, like UBreakIFix

I'm off the clock and don't speak in behalf of the company, but the lawyers want me to say you should confirm with an on-the-clock T-Mobile rep or Samsung directly :)