(any Flatpak user would’ve at some point run into annoying sandboxing limitations - such as password manager and browser integration, or themeing woes)
While I overall do prefer Flatpak over AppImage these days, the sandboxing has indeed been giving me more trouble than I think it is worth so far.
Neverwinter Nights (the first one) and Heroes of Might and Magic (3 and 4). They’re just so comfortable for me to play so I just start them up when I’m to stressed out to play anything new.