I had that happen with the original Microsoft Ergonomic Mouse. The Magic Mouse has been fine. In fact it's my favourite mouse design ever, and I absolutely love the touch surface.

The bottom charging is kludgey, and there was probably a more elegant solution. But you only need to charge the mouse once ever couple of months, so it's not a huge problem.

However, I would guess my hands are not the same size as your hands. You don't have to be a design genius to understand there's a ton of variation in hand size, and one-size-fits-all products don't.

A genius product would be a resizable mouse with an auto-resizing guide to help you pick the right size and curve for your hand size and grip style.

Are you still experiencing pain? I had terrible tendonitis from playing too much chess using crappy trackpads in college lol. Took using https://www.amazon.com/Evoluent-VM4R-VerticalMouse-Ergonomic... this for a few years to fix my hands. Now I'm fine using the macbook trackpad all day.