Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Microchip Technology/ATSAME51J19A/PM/BKUPCFG#0x0
BRAMCFG=RET
Backup Configuration
Ram Configuration
0 (RET): All the backup RAM is retained
1 (PARTIAL): Only the first 4Kbytes of the backup RAM is retained
2 (OFF): All the backup RAM is turned OFF
https://github.com/cmsis-svd/cmsis-svd-data