I to have the 2019 sprint allez disc and notice ever so slightly that there is play with the adapter. I haven’t figured out a solve but I’m hoping the 5mm spacer takes care of that. The ultimate solve is the figure out the spacing for the disc brake.
Have you noticed the thru axle adapter on your drive train side pressing onto the outside of the frame and indenting the frame? Seems like there should be some kind of rubber stopper or something to cover the metal on metal and in some cases metal on carbon.