Does this mean that debt has been passed over to collections or not?

Hi all! I racked up a $1.2k credit card debt with Citi two years ago. My account was closed and the debt was passed off to UBC. However, I just got a letter from them offering to settle for about 50%. In the letter, it said that they were gathering the debt on behalf of Citi. Does this mean it hasn’t officially passed on to collections? I looked at my FICO report too and it reports 0 delinquent accounts.

Sorry if this is a stupid question! I’m really trying to build my credit score back up and I’m wondering what the best way to do it would be for this scenario, since I heard UBC doesn’t do pay for deletes.