Application runs out of memory after compressing many images

Im working on a side project to create a archive and im stumped at this one problem, i didnt encounter this problem before and i need to ask it here, the main issue is in ImageGrabber but i would appreciate if you would spot other bugs
https://github.com/wick3nd/SEP-packager/blob/main/src/SEP%20packager/ImageGrabber.cs

GitHub

SteelEngine Package packager is a file compressing program for a in progress game engine - wick3nd/SEP-packager