I think they're the default profile pictures from Amethyst. Mine was a robot thing when I started.
Discussion
THANK YOU!
Now I know where to look 🙏
I looked into it a bit more and if these are the pictures you are talking about, they come from something called "robohashing"
Link: https://robohash.org/
Yes! And that’s the term I stumbled across in connection to paynyms but couldn’t connect with nostr/amerthyst; granted my search was rather shallow.