Damper front wheel after repair unevenly long

After inexplicable vibrations, so from about 135 kmh, I had the balancing on the front wheel checked. It turned out that the front wheel had probably not caused it. Only when the front tyre was installed (you could not push the thru axle in parallel ) much notice that the left front wheel damper was about 1.0 – 1.5cm longer. See photo. But exactly this damper, had only been repaired a few months ago, because it sweated. How can it be that you did not want to have noticed this in the BMW workshop when it was installed? Otherwise you should have been stunned, that the damper is now longer. My question to the BMW workshop was = What went wrong during the repair? After I asked the request and sent a photo with me. Answer BMW = This looks funny, but nobody would have repaired this so, we have to check it before in the workshop. My question to you = Who had something like this before? What exactly was the cause?