Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32n6/STM32N645/ETH/ETH_DMAC0TXRLR#0x0
Channel 0 T0 descriptor ring length register
Transmit Descriptor Ring Length
https://github.com/modm-io/cmsis-svd-stm32