L.W.
My kids go to the potty less and wake up dry more when they are at grandparents' houses, too. I am convinced it is because they don't drink as much there. They are playing and not drinking. I know that when I was little my mom gave us significantly less to drink than I give my kids.
I have also heard that kids are more likely to wet the bed when they are at home because they sleep more soundly than they do at someone else's house or on vacation. They don't wake up to potty or they get into a deep sleep at home and don't hold it well.
You mentioned that you have moved a lot in the last three years. Has there been a big change like that recently? Maybe that has also contributed to it.
Good luck!