I’ve been seeing this as well though not as drastic and have been scouring the Internet for an explanation to no avail. I’m not using adlist, and memory usage has been steadily ticking up while the number of cache entries remains steady. I changed my DNS arrangement to have Pi-Hole hit Cloudfare directly (had it going through the RB4011 to work around a previous issue) and flushed the cache, but memory usage barely dropped despite going from ~3k entries to <200. The only thing that makes sense to me is that there’s a memory leak. I saw a post somewhere (Reddit?) where someone claimed their issue was resolved by changing a CNAME record to an A record. I do have a several static local CNAME records, but changing them isn’t an option.