Manifest icon url generation not working properly when using an external media server

[Gandhi11]

If you site is using a plugin like WP Offload Media and all the medias are store in a bucket S3 for example, the the URL generated for the icon in the manifest a not working properly.

I suggest using the default get_site_icon_url() function https://developer.wordpress.org/reference/functions/get_site_icon_url/ from wordpress to properly get the icons informations instead of generating the url of the different size yourself.