although in reality, you load profile picture once, you can save whatever quality variant of it in local storage. if someone wants to waste your bandwidth, they can post single post with 100x 500 MB gifs anyway. you could add soft recommendations of picture sizes in spec for all images, as well as bandwidth saving setting which prevents automatic loading of images past specified size. also it could still be beneficial to have two image qualities for all image posts. often its not necessary to load 8K image in feed, but photographer may still want to publish original high quality image.