https://www.wentworthpuzzles - mine is the 24 day; they also have a 12 day. They’re wooden puzzles from the UK.

I have to air out the pieces(shake them in a mesh bag outside) because the fine sawdust gets to me. That’s my only caveat, otherwise the quality is great.

I’ve seen other “advent jigsaw puzzles” around from different companies if you don’t want a wooden set.