I don't know when this change was implemented in PiHole, but sharing just in case it helps someone:
If you have previously used the dnsmasq workaround to have multiple conditional forwarders in PiHole, this feature is now directly supported in the UI, but the caveat is that the old workaround no longer works, you need to move it from the .conf files to the UI. #PiHole #DNS #SelfHosted