Steep contoured wrist rests are probably worse with a vertical mouse.

Yes, I think they increase strain. A vertical mouse already puts your forearm in a neutral handshake position—the whole point is to keep your wrist straight. Adding a steep, raised wrist rest can push your wrist into extension or tilt it sideways, working against the mouse’s design.

Most contoured rests are made for traditional flat mice, where your palm is pronated. With a vertical mouse, your forearm is already rotated. A flat pad lets your wrist rest naturally on the desk surface without forcing a bend. The steep contour can create a pressure point under the forearm that encourages you to lean into it, tightening the muscles.

I’d go with a neutral, flat gel or foam pad—or no wrist rest at all. Your forearm should move freely, not be propped up by a bump.

If you’re already comfortable without a rest, don’t fix what isn’t broken.