Add a spacer between the trainer and frame. More accurately: if you install a sleeve around the threaded section of the QR adaptor, it will reduce the depth it can screw into the trainer which results in the drop-out spacing being increased.
This is nearly par for the course with a lot of trainer and bike combos.
My approach would be to measure the diameter of the threaded section of the adaptor so you know what the inner diameter of the sleeve should be.
I just measured the thru-axle adaptor from a Tacx NEO/Flux and come up with 16.76mm across the threaded section. If yours is the same (BIG if), you could source the Tacx sleeve, part T2844.15 and use that.
Yes, but it felt like it was “too wide” or at least wider than necessary. I think I’ll keep my current solution for a few rides and then examine the frame/dropout again more closely. At least for now this seems to work fine.
I ended up removing a few millimeters of the metal where it touches the frame with a grinder and fine sandpaper. This is hardly noticeable and seemed sensible to me. This way I don’t cause any damage to the frame and the damage to the roller trainer is so small that it doesn’t limit its functionality. All of this at my own risk, of course, I understand that both Canyon and Zwift have to be consistent in their communication in order not to be responsible for negative reports and consequences.