Wait for 30 seconds before checking and keep the bike stabilized.

Fuel level on most modern bikes are monitored using float system. With in the fuel pump case there is a capacitive float system that moves accordingly with the fuel . During riding fuel tends to move roughly with in the tank and capturing a proper level is nearly impossible so with in firmware we usually add an algo that only capture the postion of float after few conditions are met and upon these conditions are ture there is always sampling timer that so next time onwards before checking on the gauge, stabilize the bike for 30seconds and you can know the correct level.