Broadly: How sad.
Musically: I caught the change and definitely thought it was unusual. It brought a mildly aggressive feel to the later section of the song.
If I'm remembering right it opens in Dm and then goes down to F#m after the first chorus. So pitch wise a shift downward, but maybe you're talking counter clockwise on the circle of fifths or something?
Edit: when I first commented I either didn't see the Strawberry Fields reference or it wasn't there yet. We're probably not talking about the same thing, but definitely give the acoustic version of Pool Shark a listen.
Your Strawberry Fields reference made me curious though and I found this interesting snippet https://www.reddit.com/r/beatles/comments/5fgser/the_famous_splice_edit_in_strawberry_fields/
Toasty!