Image Filenames - How many words are considered Keyword Stuffing?

Hi there, I'm renaming images for my shopify store for products. I'm including keywords so they come up easier on google search/images. I heard you should only use like 4-6? I'm using like 15 words.

I have no officially read anywhere that google dings you for having too many keywords but I'm guessing there's a limit?

I read online by some people who claim they are "SEO" people that more than 7 keywords is considered keyword stuffing, and google then ignores your file cause it considers it as spam.

What is the real answer here guys?