Topmost Layer issue - cooling or what else? - (images!)

Hello hello!!!

Here is my first topic, and how about starting with an issue that I have not yet managed to find a similar one around!

So the topmost layer gets printed fine, however the filament changes colour, -or loses the colour- a tiny bit after finishing the print!

What can be the issue? And how can be solved? (images at the bottom)

Printer: Bambu Lab A1
Filament: Sunlu PLA+ or Bambu Lab PLA Basic

Thank you all in advance!!!

Have a nice and productive day!

Hi, try reducing the speed of the topmost layer