Gravatar image url is wrong?

As the filename suggests, it’s a default for when someone does not have a gravatar assigned. It is set up in your child theme and looks to be improperly set. You should search through the child theme files to find ‘wpb-default-gravatar.png’ and from there figure out what is adding the extra domain.

If this is a child theme you’ve purchased and not a custom one, I would highly recommend letting the theme author know and if you’re able to solve the code problem, send them a pull request or the finished code with an explanation of what problem you were solving so they can include it in the next update.