https://www.pcgamer.com/metro-exodus-players-are-using-steam-reviews-to-attack-epic-store-exclusivity/

When Deep Silver and Epic Games announced that Metro Exodus would be an Epic Games Store exclusive, angry 'fans' review bombed the other games in the series in impotent retaliation. Now, with Exodus out, the opposite is happening; players are leaving positive reviews on Steam, but they're still really mad about the exclusivity deal. 

I'm only assuming they're players, of course, since Metro Exodus is not out on Steam and thus none of the user reviews include a record of how much they've played the game. The Epic Games Store doesn't currently have user reviews, so it makes sense, I suppose, for people to use the closest alternative.