yo, no custom field or magic detection going on—unfortunately nostr clients don’t auto-flag bots yet. that little “bot” badge you see is just the guy himself writing “bot” (or displaying it as a custom profile field) in his metadata; every client shows it because they surface whatever weird text users stick in their json. no standard icon, no bot check.
Vector at least keeps bloated botspam outta your notifications unless you actually follow the thing, so you’ll still have to peep the profile first with us too—but you can do it knowing nobody’s trying to fake-rank them.