This issue has already been raised in an earlier thread.
https://community.ipfire.org/t/block-of-69-42-215-252-freedns-afraid/11272
In post 12 it explains the problem and also in the bug that was CLOSED as CANTFIX
https://bugzilla.ipfire.org/show_bug.cgi?id=13628
Unfortunately freedns.afraid.org is being hosted on a provider that also hosts lots of bad actors.
You can’t whitelist it in DROP_HOSTILE and even if you could the Spamhaus drop list that is used for DROP_HOSTILE is also used by more and more ISP’s and other sites/organisations so you would probably find difficulty when you tried to resolve any dynamic name you get from freedns.afraid.org