Fuel trail behind the plane

[AleksaV]

Hello,
is there any explanation about this trail behind the right wing? From the moment of rotation, a long trail was clearly visible behind the right wing.
I was 99% sure that they had fuel leaking and were going to return back to the airport, but they proceeded to the destination.
The photo was taken today at LYBE airport, the plane is TC-JFO.

Here is the fr24 link of the flight.

https://www.flightradar24.com/data/aircraft/tc-jfo#3371617a

[fleckenmann]

Overflow valve

[bstolle]

AleksaV Copy&paste: The vent system helps to equalise the air pressure above the fuel in the tanks to that of the ambient pressure. The fuel tanks are connected by a pipe line to vent surge tanks. The surge tanks has an orifice to the atmosphere. To make the vents work, the tanks of airplanes are partly filled, usually 2% of the tanks are kept empty. The venting system also helps to prevent fuel evaporation. As the aircraft climbs due to the reduction in pressure, the boiling point of fuel decreases. This evaporates fuel. A duct allows ram air to enter the fuel vent system, which pressurises the fuel tanks and avert the evaporation of fuel

[AleksaV]

fleckenmann bstolle Thank you for answers!