Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Infineon/XMC4300/USB0_EP1/DOEPTSIZ_ISO#0x0
RxDPID=value1
Device Endpoint Transfer Size Register [ISO]
Transfer Size
Packet Count
Received Data PID
0 (value1): DATA0
1 (value2): DATA2
2 (value3): DATA1
3 (value4): MDATA
https://github.com/cmsis-svd/cmsis-svd-data