There appears to be variation in the wobbliness. I checked out a friend's 13" M4 iPad Pro, and it was less wobbly than one I checked out in-store and less wobbly than your description. It's also always possible that some tables aren't completely level which would change the result.I just got the 13” version and it absolutely rocks all over the place, and is far worse than my M2 12.9” was. I saw people talking about it online before mine arrived but i was actually quite surprised to discover how bad the issue is, tapping anywhere above the middle of the display makes the entire thing rock back on itself
However even for my friends less wobbly unit, I think a couple of silicone bumpers on the bottom of the hinge could be useful for some people.