Just to let you know, here MX Linux 21.1 GIMP 2.10.32 from the MX repo (thus NOT a flatpak),
Click on the Foreground color, use the pipette, this works just fine as intended (I'm using Xfce desktop environment, not MATE, if this can help to narrow the problem)
Click on the Foreground color, use the pipette, this works just fine as intended (I'm using Xfce desktop environment, not MATE, if this can help to narrow the problem)