Yup. If it’s important enough that devs now have to add a disclaimer on the store page, surely devs shouldn’t be allowed to circumvent that by adding it later. Since SteamDeck customers are affected by this the most, it’s weird that this isn’t already a rule, particularly for games that are SteamDeck verified.
Aside from better server side detection, which is I agree is severely underdeveloped, I’d say that the next big step should be a much bigger reliance on reputation-based matchmaking, ideally across games. It would need to be built in a way that’s not abusable by devs or trolls and should be as privacy-respecting as much as possible (as in, not having to validate with your ID South-Korean style), which isn’t an easy task. Working properly however, it would keep honest players from seeing any cheaters at all with no client-side anticheat required at all, which would be nice.