I too had the “graphics too old” error on WoW out of nowhere a couple of weeks ago, after playing it on Linux just fine for years, no idea what changed on their part. Blizzard never supported Linux AFAIK but their games usually work nonetheless.
My PC was really too old tho, almost 10 years, it still worked fine but graphics drivers weren’t update anymore and that created a lot of problems in different games unfortunately, not only WoW (BG3 for example was full of graphics bugs - pretty unplayable, even if the PC could run it at medium settings).
I was already planning on building a new one and now it’s done, just reinstalled WoW with Lutris and it works, I used the battle.net script here: lutris.net/games/world-of-warcraft/.