This behavior does not appear to have changed since V6. It appears that the Gumball scale handle stays the same size on-screen only up to a certain zoom level, when zooming in further than that, it starts to get bigger.
Or, perhaps it’s the inverse of the above, when you zoom out, it never gets smaller than the value in the Gumball settings. The move and scale handles are 2D screen space objects in that they always face the camera (like dots and arrowheads). The rotate handles of course do need to be relative to 3D space.
In any case one can type _GumballScaleMode and change the mode to Relative and adjust the factor - this way the scale handles and the Gumball itself will always stay the same size on screen no matter what zoom level or object size.
This is somewhat confusing as I think the terminology used is inverted - my feeling is that “Absolute” would indicate keeping a fixed size and “Relative” indicate that the size varies “relative” to the the object size. But in fact it is the opposite.
And it is also strange why this particular setting it is not available via Gumball settings but instead needs to be typed at the command line…