This happens because SM artists are never exclusively just musicians that's why too many people are involved in their music.

Literally the ONLY part of the song that sounds similar (imo) is half of that one line in the pre-chorus of Back to You and the "people come, people go" line of Love Shot's bridge. Everything else sounds like it's own unique song.

I'm not a 1D or Louis Tomlinson fan or an EXO stan so I'm being very objective, and the songs sound different, at least enough to where it's rather ridiculous netizens kicked up a fuss about the so-called "similarities". The songs have totally different vibes, I would've never associated the two together. What people need to understand is that just because SM added those extra names to the credits on one German site does not necessarily mean they admit to the plagiarism accusations. These people are professionals, they more than likely understood that conceding and adding the names was a much economical and quiet way of dealing with the situation: engaging in a lawsuit war just wasn't worth it to them.