If you have a Walmart card, there’s a similar annoyance with the Capital One app on my phone. The screen to pay your bill scrolls up and down just fine, so you can scroll down to pay. The screen to redeem your collected points for cash back? Yeah, no. The screen doesn’t scroll, so I can’t get far enough down to swipe the submit widget.
My folks’ cats will eat that cardboard box. Seriously, they have to be really careful not to leave any boxes out.
Librewolf supports letterboxing as well, though the setting might be disabled by default