On a script info page it shows its icon from the script meta block
It shows the icon for this script here.
I console i have:A resource is blocked by OpaqueResponseBlocking, please check browser console for details.
and in Browser console:21:03:34,359 La ressource à l’adresse « https://api.iowen.cn/favicon/get.php?url=greasyforks.org » a été bloquée par OpaqueResponseBlocking. Raison : « after sniff: status code is not in allowed range ».
and Unauthorized for:
view-source:https://api.iowen.cn/favicon/get.php?url=greasyforks.org
Seems your script can't extract data: image.
By example for this script: Greasyfork Set Edit+
Its icon is:
// @icon data:image/png;base64,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