last month I noticed strange marks on my footage. I don't remember to see them before. I am quite sure that is not a camera problem, because I tried to record with two different Panasonic GH 2 cameras, one GH 1 camera and smal HD Panasonic camera. I also tried to change a graphic card and my SD cards, but didn't help. The marks are most visible on white walls in strong sun and on the blue sky. (You can see the marks on the video attached. This two video clips are exported from editing software. On clips I added brightness, contrast and sharpness so you can see better the marks. But the marks are visible also on raw footage)

I checked different topics on Personal view, but the only similar topic I found was Panasonic GH4 glitches/issue from Tjibbe. My problem is similar but it is not really the same.

Any suggestions?

Link to video clips (On the first clip look the marks on the white wall of the house. On the second clip look to the blue sky):