Rotten Tomatoes claims not to have found any evidence of tampering with the audience score for The Last Jedi[0]. Certainly, an assessment of fan reactions in comment sections and on youtube shows a quite genuinely divided reaction to the movie.

Let's wait for Black Panther to be released publicly before getting hysterical about what some random facebook group might try to do.

[0] https://www.forbes.com/sites/robcain/2017/12/20/rotten-tomat...

http://archive.is/FMAA5