Steam Deck black bars on Beyond Good and Evil: 20th Anniversary Edition

Hello,
I installed Ubisoft Connect using Heroic Launcher on my SteamDeck and added it to the Steam as a Non-steam game.
I ran it in Gaming Mode. Top and bottom black bars were there but I fixed it by setting scaling to "stretch". Unfortunately it only fixed it for a launcher, but when I run the game, the black bars are still there.
I know it's not strictly Heroic Launcher problem but maybe someone can guide me how can I fix that. I feel like it's a problem of a "game in a game" because I open Ubisoft as a game and then the game (Beyond Good and Evil) itself in it.
Any ideas?
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