There's no greater harbinger of potential legal issues than success. In a reading more generous to plaintiffs in the scores of lawsuits that pop up around successful artists, creators and businesses, you could assert that it's the success that brings the infringement to light; the aggrieved doesn't know they've had their idea infringed upon until they see its likeness in the news or on their screens or devices. You could just as easily say that some see a chance at a possible payday in those same stories. Both are undoubtedly true, but the determination of the measure of each is a matter of your outlook on the state of the legal system and the world as a whole.
The latest star in the hopper is Lady Gaga, still basking in the glow of accolades for her star-making turn (as an actor, at least) in, fittingly, the most recent iteration of A Star is Born. Having won an Oscar for the song "Shallow" from the film's soundtrack, she's now won the opportunity to defend herself against a lawsuit claiming the song has stolen from another artist's work. (This is separate and apart from Bradley Cooper stealing Sam Elliott's gruff, folksy demeanor and particular cadence —while sharing the screen with the man, no less— but I digress.)
The plaintiff, Steve Rosen, claims that "Shallow" steals a particular three-chord progression from his own song "Almost" that dates back to 2012. Rosen is of course seeking considerable damages for the alleged infringement, and Lady Gaga and her legal team are of course denouncing the suit and vowing to vigorously defend against any such scurrilous claims. It's rote in the positions assumed by each respective side , and in the questions asked about copyright as it applies to music.
At the heart of this and so many other lawsuits in music is the question of what makes a song unique. Any song is just a collection of notes created by instruments arranged in a new way, and it's that arrangement that gives any composition status as a new creation. But music is made up of only so many notes and so many chords, and given the profusion of songs in the digital music era, the odds of any two songs sharing a particular three chord progression is pretty great. How the matter is adjudicated might offer a sign of how copyright and music are meant to coexist — or not.