It doesn’t have to be a foregone conclusion that GLP-1 causes muscle loss though. The primary reason for the muscle loss is the reduction in calories and protein intake. If you want to keep most of your muscle mass you can just make sure you keep up with your daily caloric and protein needs.
Muscle requires protein, yes. Unfortunately, we don't get to keep unnecessary muscle just by eating protein. The body requires a lot less muscle to lug around 200 pounds than it did when lugging around 300 pounds.
We have to do the strength training. "Use it, or lose it".