I tested the push on iOS 13 beta 3 with UPS 2.3.2 and It does not work for register the device.
Debuging the app I figured out the device token changed from String to byte array.
2019-09-12 10:50:43.741894-0300 AeroGear Cordova Push Playground[569:213854] WARN: {"deviceToken":"{length=32,bytes=0x83bbdb16b2644902497ef86ef08ac7cf...818e506aa24e0b6c}","deviceType":"iPhone10,4","operatingSystem":"iOS","osVersion":"13.1"}