Is this some kind of USB enclosure? I see issues detecting some USB disks, nothing much you can do on the Unraid side, try connecting the disks to a different USB controller or using a different bridge/enclosure, or better yet don't use USB and connect them to a SATA controller.
Strange that the permanent syslog didn't show this but the current syslog does:
Oct 20 00:43:49 server kernel: macvlan_broadcast+0x10a/0x150 [macvlan]
Oct 20 00:43:49 server kernel: macvlan_process_broadcast+0xbc/0x12f [macvlan]
But that's good news since Macvlan call traces are usually the result of having dockers with a custom IP address and will end up crashing the server, switching to ipvlan should fix it (Settings -> Docker Settings -> Docker custom network type -> ipvlan (advanced view must be enabled, top right)).
6.11.1 fixed that issue for some but not for everyone, hopefully it it be fixed for all in the next release, but in case it's not that try a different browser and make sure there ar no ad blockers or a firewall blocking the GUI.
Oct 17 04:45:37 Tower kernel: macvlan_broadcast+0x10a/0x150 [macvlan]
Oct 17 04:45:37 Tower kernel: macvlan_process_broadcast+0xbc/0x12f [macvlan]
Macvlan call traces are usually the result of having dockers with a custom IP address and will end up crashing the server, upgrading to v6.10 or later and switching to ipvlan should fix it (Settings -> Docker Settings -> Docker custom network type -> ipvlan (advanced view must be enabled, top right)).
Parity swap will use the old parity for the disabled disk, but that won't work in this case since it will be the same size as the previous one, you'd need to then rebuild again to a new larger disk.
750W should be enough, assuming the PSU is OK and decent quality, syslog should save the log wherever you configured it to, but enable the syslog mirror to flash option, that will save it to the logs folder.
Yes, it's a bug, if you click on "shares" you also see the old pool in the name, but if you click on a specific share you see the new pool in the drop down, it is a corner case but I will report it to see if it's fixed when possible.