I've been told by support that the Query Builder has become a legacy object, meaning it hasn't had any development in a few years now and isn't officially supported in iSAMS hence why it might be removed at some point.
Please don't remove it because it is very helpful searching a group of students with different fields e.g. searching all Year 7s that have the ethnic group of Black Caribbean because SLT have asked for a quick number or bring up all the Year 10s that are missing UPNs because school office need to chase etc.
There are no plans to deprecate Query Builder, in fact, it has been improved recently.