To preface, I am a student, so hearing this isn't too unfamiliar. But at the same time, I wonder if it's something normal to hear.
I heard this the other day when trying to format printing in an interpreter I was working on. The solution was so simple that, indeed, as my friend noted, I was overthinking things. When someone says "You're overthinking it," how does it make you feel?
I heard it a few times in the past, my reactions is always "there should be an easier way to do it and I'm not noticing it 🤔", it's usually followed by a "how would you do it?".