ᐅ Discoloration Issues with Rehau Softline Profiles

Hello forum experts,

I hope you can help me. When building our house in 2009/2010, we chose Rehau Softline Brilliant Design profiles (golden oak / white). The white profile sides (the interior parts) have discolored. It looks as if someone has precisely rolled a gray roller over the profiles. Next to this, there is a white edge that looks like it was drawn with a ruler. We can observe this on all the windows. To illustrate better, I’m attaching a photo.

I wanted to get your opinion first before my window installer tells me anything.

Of course, we are a non-smoking household (no stove or anything similar either).

I look forward to your feedback!

Please take a picture from a greater distance.

I’ll do it later then.

Adhesive residue from the protective film? Can't get the haze off at all?

I can’t get a better picture that easily.
@Lexmaul79: The protective film idea might make sense. However, we removed it shortly after installation. Also, the windows are fully cleaned every 4-5 weeks. Do you know if the haze is a common issue? What can I do about it?

It's just a guess – what do you use to clean them? Do you have isopropanol? Slightly soak a cloth and rub in one spot...