Watch face

You need to quickly return to the Apple Store for them to examine. You don’t say what exact model you have. If it a 3 or 4 it might be still under warranty. They at the Apple Store Will make that judgement call

Same thing happened to me... Just looked down this morning and my watch face has come loose. Just so happened to be a month or so after my warranty expired. (go figure). Apple support said it would be a $265 repair plus shipping and fees. I am stuck with a broken watch...

https://www.macrumors.com/2018/04/14/apple-watch-s2-swollen-battery-service-policy/

Ok doesn’t look good! Follow the advice of deggie