Airlines do not dump toilet waste out of the airplanes during the flight in the air.
The airlines cannot and are not allowed to dump toilet waste and sewage from the airplane while in the air and there's no way for them to do so.
However sometimes there are some leaks from the sewage tank fittings that can leak out which is normal but there's not a lot of sewage that comes out.
When the airplane lands they have people clean the tank out and remove the waste and then they dispose of the sewage somewhere else.
But they do not dump the waste in the air.
The planes have a holding tank for sewage like campers and RV's do but in a larger scale.