Q: Continuing from that question I asked you about what a borrowed chord was, another name it could be called is modal interchange or mode mixture. Still have any idea what it is?
A: that would be like if your song is in C but you use a chord from slightly outside of C. like Bb, Eb, or Ab, which are actually a part of a C minor key but not C major. using those chords in a Cmaj song is actually pretty normal and legit, and it is most likely the thing you are talking about