Probably bought an e-bike that was the wrong size or it's geometry is made to give you a position you don't want to be in.

Also, aging bodies in retirement frequently have their muscle mass wasting away from lack of activity for those muscle groups. Particularly the core body muscles that allow you to cantilever your body from the saddle without bearing excessive weight on your arms, wrists and hands. In my younger days, I thought going to a gym was silly. Now I'm learning it's pretty much a necessity if one wants to stay comfortable on a bike.