After upgrade from 6.2.3 to 6.2.4 multiple false "multipath count changed" alerts were received.
Real items discovered by:

vmware.hv.datastore.multipath[\{$VMWARE.URL},\{$VMWARE.HV.UUID},\{#DATASTORE}]

The interesting part that most of the checks were still working correctly and the issue appeared only for some datastores, but for many hypervisors:

The items started to collect 0 instead of 4!

Relevant LUNs were checked manually via the vmware provided interface, all 4 paths are available for each.
Since the issue started to happen exactly after the minor update (seconds after), this has to be a bug.

After making zabbix-server downgrade back to 6.2.3, the items again collecting correct values (>0) and the false alarms now being resolved.