Belize is a “Commonwealth realm” - a country where the Queen is head of state. In the year 2000 they changed their oath:

“I, [name], do swear [or solemnly and sincerely affirm and declare] that I will bear true faith and allegiance to Belize, and will uphold the Belize Constitution and the Law, and that I will conscientiously, impartially and to the best of my ability discharge my duties as [ ] and do right to all manner of people without fear or favour, affection or ill-will. [So help me God.]

There’s no reference to the Queen at all.