After a Square Enix update to the launcher earlier this year broke compatibility with Final Fantasy on Steam Deck, Valve managed to get it back up and running, and the most recent rollout of the experimental launcher for Proton is what made it possible.
If that is the MMORPG that you prefer to play, then by all means, update to the experimental version so that you can enjoy the game regardless of where you take your fancy handheld PC.
The experimental branch now also makes other games playable, including the following: Some of the titles included in this compilation are Age of Chivalry, Chrono Cross: The Radical Dreamer Edition, Saviors of Sapphire Wings/Stranger of Sword City Revisited, and Xenoblade Chronicles X.
Iragon: Prologue, One Piece: Pirate Warriors 4, Atelier Meruru, Warhammer: End Times-Vermintide, Star Wars Episode I Racer, The War in the East, written by Gary Grigsby, The War in the West, written by Gary Grigsby, Some of the titles that have been released recently are: Beneath a Steel Sky, We Were Here Forever, Cities XXL, Cladun X2, Succubus x Saint, and Cursed Armor.
The update also includes fixes for crashes involving the Elden Ring and the DEATHLOOP.
To speak for myself, the concept that Gary Grigsby’s War in the East and West could be played on the Steam Deck completely astounds and astonishes me. I have no idea how you would play those, but I guess I’ll have to give it a shot now.