and gasses from the muzzle get sucked into the engines while firing.

Not true. The engines are mounted where they are, to prevent that.

IIRC from the A-10 show on Military Channel, the engines are mounted
where they are to give the plane better survivability against AAA. That
dictated placement of the engines. One could be blown off the airframe
and the plane could still fly. The trail of spent gas from the gun was
fairly obvious in the airborne footage of the gun firing IIRC. Also
mentioned in the narration. Also mentioned was the recoil slowing the
aircraft. If this is not accurate then the Military Channel has poor
sources.