Has a lender ever offered you a first-time home buyer grant in your loan estimate and then denied it after underwriting?

Hi! I am in the process of reviewing loan estimates from lenders for my co-op purchase. I got 4 estimates and have already struck down 2 that have high rates/unsavory terms. One of the remaining lenders offered a $7500 first-time home buyers grant and it put me over the moon with joy at first. This is my top pick.

But now, the doubt is creeping in. What if the grant is just bait that the loan officer is using to hook me? What if I go with them and the grant ends up being denied for some reason when it comes out of underwriting? I'd feel like I would have been tricked!

This lender is a bank and I don't hold an account with them; I originally submitted my info to get pre-approved for a different co-op unit that only they were willing to lend on, but things fell through there and I just decided to keep them in my back pocket. I've scoured their website looking for the fine print regarding their grants and didn't find anything. But that has not put me at ease.

Has anyone had the experience of being offered a grant in the loan estimate and being denied afterward? If so, why were you ultimately denied?