Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32n6/STM32N645/ETH/ETH_MACA2HR#0x0
SA=B_0x0, DCS=B_0x0
MAC Address 2 high register
MAC Address1 [47:32]
DMA Channel Select
0 (B_0x0): DMA Rx channel 0
1 (B_0x1): DMA Rx channel 1
Mask Byte Control
Source Address
0 (B_0x0): DA
1 (B_0x1): SA
Address Enable
https://github.com/modm-io/cmsis-svd-stm32