The window frame is bulging. What is that?

Hello everyone,

my sliding door has a bowing downward. What do you think about it? Unfortunately, it is hard to photograph this bowing. I tried it once.

The frame sounds a bit hollow when you tap it.

Thank you very much!

Of course the frame will be hollow, hollow chamber profile for better thermal insulation. Unfortunately, as you already say, you can't see anything at all in the picture.

Maybe it will become clear now (sometimes with and sometimes without marking).

And one last time. So to speak, the second element from the glass going upwards.

Hi,
in the photos there really seems to be some bulging. But hold a straightedge against it so we can see how much it really is. Is that mm or cm?

Best regards,

Andreas

I find it rather wrong elsewhere...