Summer of 2023, dh and I took a west coast closed loop cruise. Our passports expired less than 6 months after our return. Since we were not stopping in a country requiring those 6 months we were ok. They did point out to us that our passports had less than 6 months, but we were fine.
On a side note, when we renewed we just got a passport card. Much cheaper and also works for most closed loop cruises. (Can’t stop in Martinique I believe. Cuba too, but we definitely will not be going to Cuba.) I know, I know…should something horrific happen and we have to fly back we can’t. I guess we’ll either have to wait and cross the bridge when we come to it, or become Mexican citizens. 😜