Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32n6/STM32N645/ETH/ETH_DMAC1TXDTPR#0x0
Channel 1 T1 descriptor tail pointer register
Transmit Descriptor Tail Pointer
https://github.com/modm-io/cmsis-svd-stm32