Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32n6/STM32N645/ETH/ETH_MTLTXQ1QWR#0x0
Tx queue 1 quantum weight register
IdleSlopeCredit or Weights
https://github.com/modm-io/cmsis-svd-stm32