It appears you are using a GraphQL request to generate users' profile pictures in Firefox Quantum (see attached). Unlike Chrome, FFQ does not automatically generate content from "getter" methods and links. What you have is an error "could not load the image" because the image does not exist at that exact address. That address is a query which resolves to a link containing the desired profile picture.
Solution: A direct link will be necessary, perhaps using JS to query at runtime.