What DOES happen to the audio when you change parts mid-flow?

Wondering if anyone has established what it is exactly that happens to the audio (momentarily) when you change parts?

I ask because right now it’s doing something I like(!) and I want to program that effect instead of ‘performing’ it.

Maybe it’s the parameter locks being overridden for a step? but i think theres more than that. In my case right now i have all four parts identical, so it’s not a product of sample changing… it’s a bit like a quick solo of track 4, but not only that… something with levels?

Anyone investigated further?