How does this seemingly random major chord affect the mode of my song?

So, I wrote this song like 2 or 3 years ago, and just now I’m revisiting it. I have been consuming tons of information about the diatonic modes recently, and I wanted to study this song I made because I knew I did SOMETHING in the chorus that switched up the mode or something like that. I just don’t know what, and I’ve been trying hard to figure it out. The two main chord progressions are these:

Ab half-diminished 7th / Gb minor (verses and bridge) – 99% sure this is just Aeolian or Minor.

Gb minor / B major (chorus) – Turnaround to verse is the first progression. Does this make the chorus Mixolydian or Phrygian? Or is it still Aeolian?

Link to a simple MIDI piano version with the melody to help:

Made an account on here for just this question lol

Hey I like this, nice work. You’re right, it alternates between minor and dorian: the verse uses the iiø7 and i chords of G♭ minor and the chorus uses the i and IV chords of G♭ dorian.

You could argue that the verse is the iø7 and vii of A♭ locrian and the chorus is the v and I of B mixolydian by focusing instead on the other chords, but they sound more dominant to me.

Glad you liked it! And thanks for helping! I think I was searching up so much trying to figure it out that I broke my brain and had to ask a forum. The minor-to-dorian point of view seems to make sense, but the locrian-to-mixolydian point of view is so weird that it’s cool, haha.