Gravity is not the only force. Other forms of force exist. Multiple forces can affect an object at the same time. Forces can counteract gravity, making an object move against the direction of gravity. These cases do not disprove gravity.
Objects can move against the direction of gravity, and flat-Earthers use it as “evidence” that gravity does not exist. In reality, there is at least a force other than gravity affecting the object, in the opposite direction from gravity, with a larger magnitude.
Aeroplanes and birds fly because their lift and thrust are more significant than the force of gravity. An object can be stationary atop another object because of the normal force. Hot air balloons, clouds, and eggs in saltwater can float if their buoyancy exceeds the force of gravity affecting them. Pieces of paper can go upward and stick to a comb because the electrostatic force attracting them is more significant than gravity. An indoor skydiver can float because the drag from the wind is the same as the force of gravity. Fridge magnets can stick to the surface of a fridge because their friction is holding them against gravity. A floating globe floats because magnetic force repels it up against gravity. A wrecking ball does not fall because of the tension from its chain, holding it against the force of gravity.
The force of gravity can even counteract each other in the form of a counterweight. An elevator (lift) that takes us up and down in a skyscraper has a counterweight having about the same mass as the elevator itself. This way, the motor does not need to hold the entire weight of the elevator and spends much less energy.
All the phenomena where an object is in motion against the direction of gravity can be consistently explained by mechanics and physics.