I'm using php 7.4. Those posts are from 2011 - 2013 and they are talking about php 5. There is something else going on that has to do with the transcoder and limitations somewhere. 

Are you able to upload and encode a video larger than 2GB in UNA, what is your setup? I can't find the solution.

Even with the newer Samsung Galaxy S20, a 2GB limit will be a problem and that is just for a cell phone video. Allow uploads to be very large and compress them into super, super tiny.