I've seen others post this topic and it has said it was solved with the answer but it is NOT solved.

ANY time I post a reel on the platform it creates black space around the reel. I have removed the video optimizer as suggested and it will not accept my original format even though it was created in instagram. Something is really wrong here, it didn't used to do this, now all my content is teeny tiny and unwatchable on all platforms. Something has got to change here please do not just tell me to untoggle the video optimizer because that is not the solution.