My question is does it Glide download the image from the URL, or just display it? If it downloads that then if it changes at the URL point it won’t change on glide. If it doesn’t download it and just displays it, any changes made to the original image on the original site will change.
Neither. Glide heavily caches your images and optimizes them per device, changing their format and resolution to load optimally for each operating system and screen density.
I’m guessing that you’re asking because you’ve updated an image and it’s not updating in your app. If so, please see How can I cause my images to update whenever they change?