Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/STMicroelectronics/STM32U599/OTG_HS/DIEPTXF8#0x0
OTG device IN endpoint transmit FIFO 8 size register
INEPTXSA
INEPTXFD
https://github.com/cmsis-svd/cmsis-svd-data