There's a few, and I dunno, I thought this skin was thoroughly tested out before release. Fortunately, they're only aesthetic.
1. When Power Chord becomes available, the particle effect appears. If you transform your mode, then it does *not* update to reflect the mode that you're in (eg. it shows the particle effects for Ethereal while you're in Kinetic)
2. Toggle mode doesn't always work. There's roughly a 20% chance of it working when you press the button, all other times it just cancels whatever action you were performing. Understandable if it was because Sona was already transforming, but this seems to happen several minutes after that.
3. Power chords pulse with a different beat to the currently playing song. Not sure if it's a bug or just an oversight, but it's quite disturbing to watch it be completely out of sync.