That is a good question.
To understand how the filter works, I tried to use various filters in the 'Allowlist' to see what comes up.
What I have found is that the filter *AAA* in here:
seems to bring all domains that contain consecutive letters (try it and you will see).
However,
if I enter the same in the 'Blocklist' field and also enter a consecutive letter domain to be searched (eg. contains 'nnn') then the result is confusing... unless what one enters in the 'contains' field has priority over what is entered in the 'Blocklist', I don't understand the results.
Could you give it a try and see if that works for you?
There is an article linked right under the filter that explains why there are 4 letters A,B,H,K to represent letter repetition.
The pattern only works with specific positions inside the domain name. So just saying "remove all 3 letter repetitions" doesn't work. You can only remove 3 letter repetitions at a specific position.
If you want to remove 3 letter repetitions in a 6 letter domain name like in your example, you have to define multiple patterns like this: AAA*** *AAA** **AAA* ***AAA
That would remove 3 letter repetitions at any position in a 6 letter domain name.