I have the following setup DJI X5S with Panasonic lumix 14-42mm/3.5-5.6 hd zoom lenses. I see the image a little distorted like fisheye effect when I look at close strait lines (let's say a door for example). When I zoom the problem is more obvious. Who causes fisheye effect - settings in DJI GO app, bad lenses, bad X5S ??? Something is broke?

Most lenses are translating the image with some amount of barrel distortion, particularly wide angle optics like this one. It can be easily corrected in post with proper lens profile applied.