The FICO score that comes with Citi cards is FICO 8 Bankcard Enhanced. It is a different model from FICO 8 Classic, which is the score you are probably comparing it to.
An interesting difference between the BE and Classic flavor of FICO is that the BE flavor can actually go higher than Classic. The top range for Classic is 850 but the top range for BE is 900. It's striking therefore that your BE score consistently lower, by a significant margin, than your classic score.
It suggest that, from the perspective of a credit card issuer, the same Equifax report looks significantly more risky than it would to a more generic creditor.
Do you have a full 3B report from myFICO? If so, was the FICO 8 BE score significantly lower than the FICO 8 classic? (Drawn on Equifax data.)
