Gap between window elements

We received new elements (1 window, 1 door) from a window manufacturer almost two years ago. Previously, we had also had Veka for nearly 40 years. Due to the convincing quality, we decided again on elements from this company. Elements of the series VEKA Softline 76 AD were installed.
Between the door and the window (transition), we have now noticed in the upper area that the gap is widening, so that it is now visually noticeable at first glance.
We are now concerned that the gap could increase over time, and even that consequential damage could occur (leakage, tension damage, etc.).

The window manufacturer informed us that this is "[…] an expansion joint […] which can change due to temperature-related expansion or contraction." It cannot be guaranteed that the gap – the visual impairment – will not increase further. The whole thing cannot be fixed/repaired, but only covered with an adhesive strip.

We are now wondering whether it really is an expansion joint or whether such extreme irregularities can occur over time and whether a repair is really not possible. Such a thing never happened with our old elements.
Masking the appearance with an adhesive strip is a "dirty" solution for us because this is not how we visually purchased the elements, and if the gap should get bigger, the adhesive strip could even come loose over the years.

I look forward to your support.

PS: Attached you will find pictures.

The explanation seems plausible to me - especially since the topic "verkleidete Fuge" also repeats above the windows. There is nothing broken there either, just unattractive.

Thank you for your assessment. Above the windows, the "covering" is original to the house, as there are two roller shutter boxes. Normally, no covering belongs between said elements. We did not have one before, it was not "sold" to us as part of the offer, and it would at least not visually harmonize with the overall appearance in the future. If a gap on a car is uneven, nothing is taped over it; instead, it is adjusted. "Unsightly" is also a defect if it causes the actual condition to deviate from the target condition. And since we are not experts, we are wondering whether it is really "only" unsightly, or if something else is behind it or if consequential damage could still occur. The joint also apparently does not move evenly, but only in the very upper area.

No defect, windows warp over time

That windows warp over time is also known to me. Such an extreme visual change, by comparison, we have not had anywhere until now. One might think that current models can "withstand" more than windows that are almost 40 years old. When the window installers were on site for something else, they were at least very surprised and puzzled. I am also surprised that it cannot be adjusted.

I am rather surprised that the frames were built directly next to each other.