That’s because performance is a criteria for getting verified:
default configuration: the game must ship with a default configuration on Deck that results in a playable framerate.
Source: https://partner.steamgames.com/doc/steamdeck/compat#DeckCompatibilityChecklist
There is no “target framerate” though, so what’s considered “playable” differs from tester to tester.
Hunt works perfectly fine on Linux, played a few rounds yesterday.
Tarkov still does not.