Produced a disturbing result for a simple prompt

I had a simple head and shoulder portrait with a transparent background. I prompted with "solid yellow background" expecting something like paint bucket fill. Instead I got an image which appears to be a mashup of different arms with hands that don't match and extra fingers that that look like internals of a rib cage.  I think perhaps using insert with the transparent background is the issue. Don't think I'll spend any more time on this to find out. I have manually erased the face of the boy for privacy reasons.