Around then, captchas were turned off by default for a short period of time (very stupidly, IMO), if I remember correctly, and a lot of bots were registered on a good number of instances. It was also when a lot of new instances were sprouting up because Lemmy was just gaining momentum.
I have personally let certain things I host go on for years without checking them, because developers have ADHD more often than not, and autopay will keep your zombie in service for a long time if it’s not making a dent big enough to make you shut it down (hosting a low-activity anything is not usually very expensive).
FWIW:
Not impossible that it’s just an absent admin.