And we've had many songwriters comment on the subject. Adam Neely is a musician-YouTuber and has a video on the Thinking Out Loud case where he argues that chords can't be copyrighted. I think this idea has pretty much been absorbed into the public consciousness.

I've seen people defend Cupid by saying it uses the common 2-5-1 progression, and I think that's correct but also it's very obvious that the Turkish song has something else going on in the harmony with it's descending chromatic notes and emphasis on (I think) the 7th note of the scale.

The harmony is not what makes them sound similar, it's the opening 5 notes of the melody which are definitely shared. However this is where I think Adam's video on Dark Horse is relevant. It's about how you can't copyright a descending minor melodic phrase. The situation here is a little different, but it's just 5 notes matching instead of 4 (and for a further coincidence 4 of the notes from the Cupid melody in question make up the Dark Horse ostinato).

And then what follows is the natural way you'd resolve this melody. Off the top of my head (and I don't even know that many songs), the second part of the Star Wars Theme and White Mercedes by Charli XCX share similar melodic destinationa although the rhythms and how they reach them are different.

Additionally, more recently, Olivia Rodrigo's Good 4 U and Dua Lipa's Levitating have also been accused of plagiarism with many people becoming convinced of wrongdoing by back-to-back comparisons of songs that do sound very similar. And Adam Neely has shown that both cases start to fall flat when you start finding other similar pop songs.

The conclusion from all of these videos is that new music is not dreamt from nothing, but rather it is drawn from a common well. It's inevitable that songs will sound similar given that there's only so many notes and everybody is working from the same cultural context where specific sounds evoke specific feelings. Despite what courts have ruled, to say any individual can own the well when they themselves drew inspiration from it is troubling. Adam has a pretty recent video that's kind of his magnum opus on the subject where he lays out what's wrong with copyright and how the system should be reformed to one that embraces quotation from the cultural canon.

One can disagree with Adam's take on the subject. There are certainly arguments to be made about how small artists need protection from their work being stolen by mega-labels. But I don't think it's defensible to decide whether a song is stolen based on two recordings played back to back and judging whether they sound similar. And we should develop an understanding of what intellectual property rights should be that doesn't automatically accept what courts currently recognize.

The stakes here aren't just whether some company and its songwriters broke the law and now that's Kpop discourse. Songwriting as an art form is at stake, and the conversation should reflect on that.

TL;DR: the essense of songwriting is a deep subject and you should really take the time to hear what actual songwriters have to say about modern copyright.

Edit: Adam just released a quick video update on the Thinking Out Loud case today, so if you want a short overview of his thoughts go check it out.