washed out rendering

hello!! so i have been using after effects for 4 years now as an instagram editor using my macbook pro. recently in march, i changed my project format to h264 for a youtube project i helped my friend work on. however, after changing my settings back to default so i can continue to make videos for instagram, i noticed washed out colors after rendering. after some research i learned that it was a quicktime error that is common with animators or video creators. the solution i saw was to leave it alone and it'll look like what i saw on adobe, but when posting my videos to instagram, they looks exactly the same as they did on quicktime. i do not plan on using h264 in the future so im not sure what to do to get my videos to look like how it used to look. here is an example using my pet tortoise