Watch Unpairs

New 11 watch running 26.2 that I got 2 months ago. This is the third time I’ve woken up and seen the alert that an Apple Watch is available to pair with my iPhone. Each time this has followed a day when I left the watch on the charger and didn’t wear it (so at least 30 hours not being worn.) My phone still thinks it’s paired to the watch, but can’t find it.

The last time, repairing took over 4 hours. Ideas of why this is happening?