Even with genuine Glock Factory magazines,
there are several generations of Glock magazines,
with different magazine bodies and different followers.
The Original Glock OLD style mags do not have metal wrapped all the way around the front of the mag body. These mags were never intended to be drop free [ European gun designers, most military organisations, and IDPA, have a different philosophy about throwing away mags than do IPSC people]
With the proper follower, the slide stop should press down about 1/8" on the empty magazine follower, which is enough to give a spring assist to the beginning of the magazine ejection, If the follower does NOT push up on the slide stop properly when the mag is empty, the weight of the mag and gravity are the only things ejecting the mag. There are several different variations in 9 mm followers, and some of them will not connect properly with the slide stop.
Some aftermarket add on "Butt Plugs" intrude into the mag well just enough to add friction to the magazine ejection.
The factory Glock EXTENDED mag release is almost a necessity for some people. Personally, I put the extended mag release on all my Glocks, otherwise, I don't press in far enough to reliably and consistently drop the mags free.
Proper technique can overcome a sticky mag ... just use the little finger of your support hand to assist the magazine out of the butt. You then can grab the mag and stuff it in a pocket for later use or, simply discard it into the mud.
Your choice.
of course,
free advice you get from the internet is often worth much less than you paid for it,
and YPMMV
[;{)
LAZ 1