Gregory's ServerThere was 1000 AP instances, generally anything with more than 100 active users reported, including mastodon.gougere.fr too, versus the first 1000 names from OONI global https://raw.githubusercontent.com/citizenlab/test-lists/master/lists/global.csv which I guess can pass as a sort of a combination of well-known and reliable but not famous names.
Unfortunately, I have not saved responses for each of the domains, only overall stats, but now that I scrolled through OONI list I can say with reasonable certainty that those few percents on OONI list resolvance failures was definitely due to the fact that it also contains several ActivityPub instances.
I'll put together more representative lists for next time, but I believe it was already a statistically significant difference.