I would assume this is two things- RAM Management in iOS/iPadOS, and also the app. This was never an issue before in iOS12 for me. Using the Mail App, Safari, and a number of other 1st and 3rd party apps.. The Amazon App has always done this, though. Switch to another app, switch back to the Amazon App, and it refreshes.. I think that's just their app. BUT, now in 13.2, I'm seeing this across the board for all apps.
HOPEFULLY Apple fixes the RAM Management issues, and then maybe at that point 3rd party app devs can update their apps to accommodate.. That's my 2 cents.