I suspect there's a JavaScript procedure within the script that is called within the upload macro.
Again, don't ask me for details. That stuff is beyond my competence.
(As a personal view, I'd argue that avatars should be small. They're just meant to be visual indicators of a post's author not to show a detailed high quality image. Consider users on expensive mobile data connections, who in any topic will be forced to download many large images that add nothing to their message and occupy vast areas of their smartphone screens, forcing them into a mix of horizontal and vertical scrolling and generally making things awkward to use.)
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.