5:30 into this video, you'll see it works fine, but 1:24:00 in, you'll see the rudder goes to the left after pushback.
What I see in that video is:
1:23:12 - GSX says "tow truck disconnected, bypass pin removed", which means it has stopped acting on the rudder.
1:23:15 - Immediately thereafter, the Flight controls check page shows the rudder is working perfectly fine, further confirming GSX is not controlling it anymore.
1:24:25 - The nose gear looks turned so, whatever happened between the previous confirmation of the rudder working normally and now, can't possibly be GSX, which at this time has already recalled the truck, so it's not doing anything.
In this one, no issue at 6:10, but it happens at 3:03:41.
Same here.
The controls page shows the rudder centered when the GSX truck is already moving out, so clearly it has released the rudder.
In fact, if you notice the external view at that time, the nose gear is turned almost completely to the left, but the rudder it's not.
The rudder is the only thing ( during the pushback, only ) which GSX controls so, the real issue here seems that is some cases, what is likely a custom variable PMDG set up for the nose steering system, which is a non-standard system ( which GSX never dare to touch, of course ), has lost its sync with the standard variable for the rudder, possibly because their code doesn't expect the rudder to be controlled by another app, even if it's only for a short while. Maybe it doesn't always happen, because the code is eventually able to re-establish the sync, but that's just a guess.