weird result by inpainting json, why?

I just successfully ran inpainting with ComfyUI as following;

I have successflly inpainted some images. However, i met the problem that the generated content is weird. Following are input , mask and inpainted result.

positive prompt:background
negative prompt:person, people, girl, child, boy, man, woman, animal, lowres, bad anatomy, worst quality, low quality

I also tested the inpaint pipeline with diffuser, the result has weird people.