This isn’t surprising at all. In this context, “Linux” means “Steam Deck,” which is basically a plug and play console being sold at cost for $300-500.
Macs actually run a lot less of the Steam library without doing pretty involved workarounds like hsing CrossOver. Since Valve sells the Steam Deck they put a lot of work into getting Windows games to run on Linux automatically. They didn’t put that effort into the Mac platform.
This is actually wrong. According to statistics, Steam deck is less than 30% of all Linux distros. It's all pretty fragmented, with Arch holding the lead at around 10% (after SteamOS of course).
Edit: fixed % cos I was way off writing from memory.
Macs actually run a lot less of the Steam library without doing pretty involved workarounds like hsing CrossOver. Since Valve sells the Steam Deck they put a lot of work into getting Windows games to run on Linux automatically. They didn’t put that effort into the Mac platform.