Formula T1S disc brake rub
Seeing the pistons extended a little is expected on hydraulic disc brake calipers. As the pads wear fluid is slowly drawn from the reservoir and the pistons extend to take up the space left by the pad wear. The pistons should retract slightly when the lever is released to back the pads off the rotor though. It sounds like that failed to happen with your calipers.
You should be able to push both pistons back. This can be be tricky as you have to put opposing force on both pistons. I have a set of tire levers that work well for this, but y9u may have to search for the right tool.
Dirty pistons and seals may be the cause of the pistons not retracting properly. You can try cleaning them and see if that helps. Park tool has a good video showing how that is sone, and it also shows how the automatic pad wear adjustment works.