Yes, a technical shortcoming in the kit's geometry. I don't like linkages where servo arm is angular and 90degrees in the rotation from the control horn's throw direction.

Given the existing setup, his only solution is to turn the servo around to "minimize" the stress on the horn. See a pic of mine. Only at full down deflection is there side forces exerted on the clevis and CH horn.

Spar

Note that this was an early setup where the ball link was not at the end of the horn, where the linkage would be closer to being a straight run to the CH horn.