Weekly scrub errors are definitely not normal. There has been a few bug fixes in Ceph & the Kernel. I would check how up to date your packages are.

Hardware errors are also possible but there has been a few software bugs so worth checking.

Here's a really curly one we recently found and solved at work (only in March) that causes both scrub errors and sometimes bluefs aborts, it's a kernel patch. Likely to happen under memory pressure:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...

https://tracker.ceph.com/issues/22464#note-50

But there have been various others.