I don't yet know what the cause is, possible the SRBs, or something to do with KW parts.

Oh btw, there's some weird shadowing off the boosters?

Might be specific to that part pack. It looks like the attachment point to me.

Gotta look at how the shadows render anyways. Turning off Ortho on 'blue background' makes a white shadow. Maybe there needs to be adjustments to the shader or turn shadows off option?

I haven't seen this happen once since. I'm gonna close this till I can replicate.

Issue is left open to remind me to force the rocket to 0,0,0 when generating image

Duplicated in roadmap