I’ve asked before but the answer keeps changing before I get around to implementing it:

My kid wants to upgrade their PC from Windows 11 to Linux. They have a recent-ish Nvidia card. I’m very technical: I don’t mind doing whatever arcane thing needs done. They are not, yet.

I haven’t run Linux on my desktop in a decade and I’m completely out of date here. What should I steer my kid toward to run recent games?

Depends on the games. If your kid wants to play anything with kernel level anticheat, it will not work on Linux, period - these anticheats don't support Linux, and either prevent the game from running altogether or disable certain online modes.

Otherwise, CachyOS is extremely popular these days, and I suppose a valid choice.

Recommend making a live drive with Ventoy. Copy over latest .iso’s of Mint, Fedora, Bazzite? for gaming.

Give them all a test drive, see what you like before committing. After install try new things in VMs.