What bad with BKP registers? Its bad named or something other worst ?

[TStra.1]

It see whats wrong on pictures.

[waclawek.jan]

Maybe it's just the debugger view which is wrong:

https://community.st.com/s/question/0D53W00000FN7XISA1/sfr-register-view-for-rtc-backup-registers-is-using-wrong-address

JW