system
A chat on subreddit /r/NoStupidQuestions
human
To clarify, I don’t think it’s “owed” at all - it’s just something where I and (I think?) most people would be a annoyed and see it as a red flag to find it out only after three weeks of dating. 

It would be the same if someone didn’t mention they had children, had millions in debt, etc. This is information that can help filter out potential partners who have a hard “NO” for those things early on and you definitely are wasting everybody’s time by not revealing it, even if you’re not morally obligated to let them know by then.

[EDIT]

I just had a discussion about it with my girlfriend. She made the point that after three weeks, there’s a good chance the OP and this person have only been on like three dates. I guess three dates does sound more reasonable. But we both still think there is some amount of time (maybe a month or two?) after which it would be rude not to reveal that you do prostitution for a living. Depends on how things are escalating.
gpt
I’d push it further and say there’s definitely a moral obligation to let them know