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Kohler Tub Spout Diverter is stuck upright. How to fix it?
Kohler Tub Spout Diverter
bathroom - Leaking Shower Diverter - Home Improvement Stack Exchange
Tub Spout w/Diverter
It is common for those to leak somewhat (they certainly don't have a tight seal, or an O-ring, in my experience (non-brand specific - you might want to call Kohler for their take) - a small leak even has the "feature" that if you shut off the water without pushing down the diverter, it will leak down to the point of dropping by itself in a few minutes, rather than surprising you with a burst of cold water from the showerhead the next day when you expect water to come out the tub spout.
"How much is too much" is mostly a matter of "does it interfere with the shower function," and "does it greatly impact water use during a shower." If you have something like hard water deposits built up in the tub spout that could certainly impact the limited extent to which it seals, for instance. That's not an issue you'd have with a whole new spout, though. But "no leak at all" is not normal in my experience.
As I recall those diverters require a strong pressure to hold them securely. If the pressure is too weak, they leak. Running the water stronger may help.