It doesn’t look like a vision. It’s just confusing. And while I assume it was that way in the theatrical cut, having Kylo’s theme burst open specifically on the shot of Vader’s helmet is kinda weird. Shouldn’t it be the Imperial March?
I’m fine with it being ambiguous.
The music has also been changed, yes. Kylo’s theme here borrowed from TLJ rather than the understated cue of Vader’s theme is relatively appropriate given it’s the first time the audience really gains any insight into why Ren is the way he is in this edit. I don’t much care for the sequels’ approach of flatly stating the expected themes when familiar symbols appear, so I wanted to change it up just a little.