On android, the button at the keyboard just opens the app, but in some cases it just takes you out of what you were doing, right? For example, logging in a game, it takes you out of the game when you're trying to look for the account through the button, and when you come back you're already out! Examples: Minecraft, requires Microsoft account, obviously, proton Pass shows you your Microsoft accounts through the keyboard, but sometimes doesn't show them all, so through the button at the right you open proton Pass, the problem is that takes you out of the game, closing it, and when you finally find your account and come back, you have to start again.

This would be different, if the button opens a pop-up, a small windows like the chrome's extension on PC. Using window's already there function, the pop-up windows.