-Stop the array, click on the now empty disk and change filesystem to reiserfs.
-Start array, format the disk
-Stop array, click on the same disk and change the fs back to xfs
-Start array, format the disk
-Done
That's from a bug a few releases ago, you need to empty the disk(s) with unbalance or manually, re-format and copy the data back, it won't require a rebuild.
Like mentioned just formatting a disk won't trigger a rebuild, but since the diags are after rebooting we cannot see what happened, disk5 errors are not logged as a disk problem and SMART looks fine, check/replace cables (both) or slot and try the rebuild again.
Unraid will still boot, just mcelog won't load, the unsupported CPU message is just about that, LT already mentioned that in the future mcelog will be replaced wit rasdemon, that one also supports newer AMD CPUs.
Then it suggests either it's not compatible with that board or the PCIe slot is not working correctly, it's not being detect on a hardware level, it's not a software problem.
Create a new test share, set it to cache yes, leave all remaining settings as default, then create a file:
touch /mnt/user/test_share/file
Then post new diags.
This looks like a filesystem related issue, check filesystem on all drives, also docker image is detecting corruption so you should delete and recreate.
FYI this won't cause sync errors.
Running a Ryzen server with overclocked RAM like you have is known to corrupt data, respect max officially supported speed for your config and see it it helps.
https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=819173