During backups, I get this, and the root filesystem goes read only.

I’ve replaced disks, rebuilt filesystems, arrays, LVM, etc.

dmesg shows:

[19501.355932] EXT4-fs error (device dm-7): ext4_get_verity_descriptor_location:295: inode #6032: comm dsmc: verity file doesn’t use extents
[19501.403496] Aborting journal on device dm-7-8.
[19501.414969] EXT4-fs (dm-7): Remounting filesystem read-only
[19501.414974] fs-verity (dm-7, inode 6032): Error -117 getting verity descriptor size

Find the file by inode:

find / -xdev -inum 6032 -print

This showed that there is junk in lost+found from when I had FS corruption.  I rebuilt the root filesystem, but never cleaned out lost+found.  Deleting the damaged files should solve the problem.