They seem to be connected to the ground on the left.
I just assume the screw dots were to mount something while providing good ground.
If you never found anything mounted on them it probably explains why there is now only solder pads - cheaper…
I found out the the other pad has a space arounf it which means it is not a ground. would be grate if it is an extra power (cool to power custom fan for the extruder motor)