I have seen a lot of people have been caught in plagiarism in recent long challenges (some of them being even 5 star).
If you want to see the list of such people, go to any long challenge before Feb Long and go to the last pages of the ranking. You will see that there are hundreds of people having 0 points and at the last rank. If you visit their profile, you will see that their rating change for the same contest is in positive despite multiple plagiarism charges.
I know that I should probably mind my own business but seeing cheaters go unpunished kind of demotivates coders who spend days and nights trying to get that AC. There is no point of catching people in plagiarism if there is no rating drop for such people.