Export as to export png moves the image on the canvas

I'm not sure if this is normal behavior but I have a png with transparency. It's meant to be use as a texture for a 3D asset so both the transparency and it's exact placement on the canvas is very important. I've been using the file>export>export as to generate my pngs but am finding that the resulting png changes the location of the pixel information on the canvas. Everything shifts towards to middle. How/where can I manage this 'feature'?