Manchester By the Sea is a 2016 USA drama by Kenneth Lonergan.
Starring Casey Affleck, Michelle Williams and Kyle Chandler.
An uncle is forced to take care of his teenage nephew after the boy's father dies.
In Australia the film was originally passed MA 15+ (like a 15A in UK terms) for strong coarse language. However the distributors preferred an M (like a PG-15) rating and so the film was cut.
The film was then passed M (PG-15) for mature themes, coarse language, violence and sexual references after category cuts.
The clue to what was cut was provided by the BBFC who passed 1the film 15 uncut for very strong language. The BBFC further commented about the strong language in its insight advice:
There is a single use of very strong language ('cunt'), employed in a sexual sense. There is also frequent strong language ('fuck' and 'motherfucker'), some of it used in an aggressive manner.
So presumably the Australian film distributors removed the use of the word 'cunt'.
It doesn't look like a film that will appeal to youngsters so presumably it has been censored for adults who would prefer not to hear strong language.