Since FTL 4.1.2 is using dnsmasq (currently at Rev 2.79 with some bug fixes included), then the behavior of FTL is dependent on how dnsmasq implements this feature. This is not a behavior that is changed by Pi-Hole.
Per “man dnsmasq” it behaves as follows:
Bogus private reverse lookups. All reverse lookups for private IP ranges (ie 192.168.x.x, etc) which
are not found in /etc/hosts or the DHCP leases file are answered with “no such domain”
rather than being forwarded upstream. The set of prefixes affected is the list given
in RFC6303, for IPv4 and IPv6.
As noted previously, this is normal dnsmasq behavior and the reason it is now seen using Pi-Hole V4.1 is the display of additional query types. It has been happening on your network, you just didn’t see it in the earlier version of Pi-Hole.
If you cannot stop the traffic at the source, and if you have concerns with your upstream DNS provider seeing this information, you can avoid that situation by using a local recursive resolver.
You may be able to block the traffic at the source with hosts file entries.