Mentioning also @Team-Hypervisor-Kernel who now manages the drivers.
Maybe it's related to https://github.com/xcp-ng-rpms/microsemi-aacraid/issues/2#issuecomment-3837183087
It looks like the switch to the vendor driver instead of the kernel built-in for 8.3 (initiated by XenServer, and that we followed at the time as it was probably made in order to support newer cards) was not without drawbacks.
0nelight created this issue in xcp-ng-rpms/microsemi-aacraid
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Microsemi Adaptec Series-8 Card not working in XCP-NG 8.3
#2