I was very-very surprised to find such a feature working after XX years experience with Zabbix...

A user macro, created directly on a parent host which has LLD rule with host prototype, will be copied over to discovered host. I.e. the user macro added not from prototype, but from parent host, holding the LLD rule.

I assume that this routine was initially introduced in code for VMWare implementation. I'd say it was a dirty hack at the time, IMO.

And now integration team started to exploit it for other templates they develop, for example for Nutanix template.

Wort to note that Tags are ignored (verified) and not copied over, while they are similar "properties" of a host, same level thing and kind on information.

This adds a great inconsistency to the the LLD engine, from zabbix users point of view!

This must be documented, at least.