Add option to strip AAAA but leave A records, so request to particular site goes only through ipv4 (or vice-versa).
Example in PiHole's UI:
[domain.tld] [checkbox to block A or AAAA] [wildcard flag]
And that's my case: My ISP is ipv4 only, and to use ipv6 I'm using Hurricane Electric 6in4 tunnel. So my ipv6 outbound is in another country. And some sites that have both A and AAAA records are frequently shows wrong country. Sometimes it leads to "content is blocked in your country" or "your traffic is suspicious" things. The way to fix this is to write that site's domain in the hosts file with only ipv4 part. But that solution is not cool.
PS: Excuse me for posting it here, but Feature Requests category is not selectable.
That will be possible when the improved regex engine is merged into pihole master (currently in development branch). It will allow you to block certain query types. I use it to block all AAAA records, but it can be used for certain domains only.
Or in other words: The next official version of Pi-hole will have it
However, I don't think a UI setting should be added. Blocking AAAA queries isn't something you should do routinely. They are always harmless. When they do cause issues, the reason in always in a bad configuration somewhere.
No, regular expressions are compiled to very efficient byte code and only this compiled form is used. You can typically run hundreds of (not too complex) regular expression against a domain in less than a millisecond. We also cache regex results for domains once evaluated to avoid a regex needing to be evaluated multiple times for the same domain.
In your case, regex is the best solution.
Regex rule is: ^www.i-do-not-want-aaaa-for-this.com$;querytype=AAAA
First Query for www.i-do-not-want-aaaa-for-this.com results in
FTL looking up the domain (not known for AAAA type)
FTL looking through its blacklist (not found)
FTL looking through the regex filter (match found for type AAAA)
---> Replied as blocked and stored in cache as AAAA:www.i-do-not-want-aaaa-for-this.com = blocked
Next queries for www.i-do-not-want-aaaa-for-this.com result:
FTL looking up the domain
---> Found for type AAAA and known as blocked