The disk "Time Machine Backups" can't be unlocked. A problem was detected with the disk that prevents it from being unlocked.
I'm running Sequoia on a 2016 MacBook Pro. I've been using this backup disk for a couple years without problems.
If I run Disk Utility, it says, unsurprisingly, that it's not mounted. Also, it's APFS Volume • APFS (Case-sensitive, Encrypted).
MacBook Pro 13″, macOS 15.3