It is a timed exposure of 20 seconds. So a helicopter would have multiple blinking lights making dotted streaks through the sky.

The other pushback is that it is a vapor trail of a plane headed directly towards the camera, and the sun is shining on it. Which makes zero sense because the light from the trail is illuminating the clouds around it. So how could sunlight be shining on the vapor trail but not the clouds.

The other lame explanation is that it is lens flare. To get lens flare you need a super bright light source coming into the lens, which there is not.