Step 1. Realize the proprietary spyware level anticheat doesn't let you.
Step 2. Play GW1.
Step 3. Realize there are no players during European day hours.
Step 4. Get Frustrated.
Step 5. Give up

Alternative route:

Step 1. Show your demand and support for Steam Deck/Linux compatibility for EA Anticheat on their forums
Link: https://answers.ea.com/t5/Other-Plants-vs-Zombies-Games/Steam-Deck-I-cant-play-Plants-vs-Zombies-Battle-for/m-p/13780421#M151491

Step 2. Hope



I love EA! I love buying a game from them and not being able to play it after an update even though the game is steam deck verified! What a wonderful company! They never make any anti-consumer decisions whatsoever. No sir.
Compatibility Tracker pages: https://www.protondb.com/app/1922560 / https://areweanticheatyet.com/game/plants-vs-zombies-garden-warfare-2/