Why OptiFine is banned in 1.15+ but still be allowed in 1.14-?

I submitted 4 runs last month (Any% SSG Pre1.9). 1 of them was rejected, but the rests haven't verified yet. I hope you guys (moderators) will verify my runs soon.

Guys will my run be approved if I separate my run into many videos?

Guys is it illegal to use night vision shader in Pre-1.9 RSG?