Had that happen to me with Last Epoch. At launch the native linux version had graphical issues where as proton ran the windows version almost perfectly.
Steam does have a monopoly though. They don’t do anything anti-competitive with it, so there is not much Epic can do about it (other than make their platform better for the people using it).
This will put pressure on studios that make E and T rated games with loot boxes (for example: Fifa). Now they have to decide between letting the game get bumped up to a M rating, losing initial sales of the game, or removing loot boxes and other gambling features.