Why does a buoyant force act on every object in a fluid?

When an object is submerged into the liquid then as we know that pressure due to liquid increase as we go deep inside the water.

So here the pressure at lower side of the object will be more due to which force exerted on the lower side of the object will be more than the force exerted by liquid on upper side.

This will cause net upward force on the object.

Let say object height is "h"

Now we can say its upper face has pressure P1 while lower face has pressure P2

so the net force on it will be given as

this net upwards force is known as buoyant force