The brass cast finger rest magazine floor plates are a little "loose"
They can pop off when the magazine is fully loaded and the spring is under maximum pressure.
the fix is to spread the bottom of he Mag body to achieve full engagement of the flange at the bottom of the mag body in the corresponding groove in the Magazine floor plate.
It can be done with a Leatherman tool
It's that easy.
The expensive aftermarket finger rest floor plates are cool and help my fat hands grip the pistol more comfortably.