At parking positions with "None" as selected pushback type and additional custom pushback paths (see first screenshot), GSX does not offer the pushback immediately but first asks if I want to request pushback (for whatever reason this behavior is different than if any default pushback directions is available instead of "None").
The reason of this behavior is because, when the Pushback is set to "None", GSX cannot possibly differentiate if "None" is an indication from the scenery developer that Pushback is NOT ALLOWED there, or it's just an oversight.
Older GSX version would have not allowed Pushback there but, later, users suggested "can we have the option to have a Pushback anyway ?" so, we added that question and Pushback would be possible even in places where it was set to "None".
Now, I see in your customization you have the direction set to "None", but you also have two Custom Pushback slots. This in fact is a bit unusual, and I guess we might just skip the question if the Pushback direction is "None" but you have extra Slots active, this is surely something we could change, because the question is a bit redundant in this case.
This never came up before, because what you have there is not how the additional Pushback slot should normally be used.
You only have TWO Pushback in total so, why not just set the Pushback direction to BOTH and have the 1st Slot in the "Left" slot and the 2nd in the "Right" ? When the Pushback is Customized, Left/Right don't have any meaning anymore, they are just two slots: you only need to use the additional Slots if you need MORE than two Slots, otherwise it's simpler to just repurpose Left/Right. The manual also clarifies this, at Page 35:
Pushback Slots
Regardless of their usage (Left, Right, Quickedit or Custom), all Pushback Slots have the same capabilities. Left/Right here is only meaningful in the fully automatic Pushback, which doesn’t involve any customization but, once a slot is customized, it’s just another slot, regardless if it started as a Left or a Right slot.
That's why the Pushback request is made: it's done because of the the "None" preference, without considering the extra Slots, which are normally used in addition to the first two but yes, I think we can change this and make the question only if NO Slots at all are available.