Run another test, if it fails replace the disk, if it passes keep monitoring, especially these SMART attributes:
ID# ATTRIBUTE_NAME FLAGS VALUE WORST THRESH FAIL RAW_VALUE
1 Raw_Read_Error_Rate POSR-K 200 200 051 - 18
200 Multi_Zone_Error_Rate ---R-- 200 200 000 - 1
If they keep climbing you will likely get new errors.
You are getting read errors on many different disks, you should see those errors on the main GUI page (and be notified about it if notifications are enabled), errors on so many disks suggest power/connection problems, you must fix that first.
It's logged as a disk error, there's a recent SMART extended test, if it was before the error run another one, if not keep monitoring, but SMART is showing some issues, so probably going to get more errors in the future.
There's something writing to the array during rebuild, disks 2 and 3 are being rebuilt while there are writes to disks 1, 6, 7, 8 and 9, this will make the rebuild (and writes) extremely slow.
Almost all disks disconnected and reconnected at the same time, including both parity drives which are using a different controller, so most likely a power problem, even if you do anything else for now you should at least reboot.
This has been reported to help:
https://forums.unraid.net/bug-reports/stable-releases/6103-samsung-980-temp-warning-r2007/?do=findComment&comment=20180
Oct 30 02:00:01 thebox kernel: md: recovery thread: check P ...
Oct 30 03:00:01 thebox kernel: mdcmd (63): nocheck pause
This suggests parity is set to pause after 1H, try re-applying the scheduled parity check settings.