FUEL CONSUMATION

Good morning to all
i have Hyundai Santafe version 2007
Before when i put the fuel in my vehicle , the indication needle of the fuel works well and it can show me the level of the fuel in the tank.
Three weeks ago, i have gone to the fuel station and i put the fuel full tank but when i start the vehicle , the needle shows me the vehicle is not full tank is little above the 3/4 of the tank. I said this maybe a small problem it maybe corrected itself for next time. Even for next time , it brings the same issue, the needle arrived at the same position as last when the tank is full. From that time i see the fuel consummation have changed. For example i was used to consume at least 20-25liters when i run 350km. From that time, when i run 300km , the needle indicate that the fuel is a little above 1/4 of the tank, which mean i have consumed more than 50liters. As you know the full tank of my vehicle is 80liters.
What can be the main reason for that needle for not working well as before and the main reason for consuming a lot of fuel than before.
i need your support and your advice what can i do.
thank you very much in advance for your support
see pictures (FIRTST ONE AFERT RUN THOSE INDICATED KM, SECOND FULL TANK)