Why is my credit score going down?

Background: My credit has always been PERFECT, never a late payment, always paid off faster than the term.

I have ONE credit card left to snowball, it's a low interest one, and I owe $5,000 on it.

I have no other debt (I just finished paying off my son's hospital stay.)

No car payment.

The land I own is paid off free and clear (I didn't have to take a loan out for it, I paid cash).

No medical debt for myself or my children.

No affirm or other credit things.

Literally everything is paid off except this card. I also have plenty in my retirement, as well as a fully stocked emergency fund. My oldest line of credit is from when I was 16, and I'm currently 33. Literally perfect credit, and my land is valued at $200k+

WHY did my credit score drop from 780 to 754?! I checked experian to make sure there were no breeches, and that my accounts are all taken care of, and they are.

I am so irritated! I want to start building a house, but I can't figure out why it keeps dropping!

Any ideas?!