Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32n6/STM32N645/OTG1/OTG_DIEPTSIZ2#0x0
OTG device IN endpoint 2 transfer size register
Transfer size
Packet count
Multi count
1 (B_0x1): 1 packet
2 (B_0x2): 2 packets
3 (B_0x3): 3 packets
https://github.com/modm-io/cmsis-svd-stm32