MangoHUD showing half the current FPS?

Playing Where Winds Meet with 9070xt ultrawide on PopOS (cosmic/wayland).

What could cause MangoHUD show half of the fps from steam's performance tracker? (note top left of the photo, the small grey is Steam)

The game feels as the higher FPS, that is why I suspect it is something on Mango. It seems to work with no problem on other games i've tried

What I've tried to change and made no difference: Gamescope, VRR/Vsync, FSR. Swapping monitors.

Edit: image on comment, didn't show here for some reason.
Edit 2: looks like whatever is happening I am not the first