battle.net.exe and agent.exe have a bad habit of dying in the background and taking down the client game with them. This MAY be what you are seeing. To rule this out, in the battle.net launcher, go to settings and set battle.net to exit completely when you launch a game. Try that, and if the problem continues, at least that one known issue is off the table for debugging.
Some things which made battle.net client stop crashing for me were:
Go to Configure options for World of Warcraft in Lutris
Go to Runner options
Disable Esync
Disable Fsync
In battle.net client, also go into it’s settings and disable hardware acceleration
Inside wow change to DirectX 11
Also I have had other problems with wayland with other apps, I use X for now and can report WoW runs awesome