you can add sub-domain by:
1- adding permission for add-on by adding sub-domain in "manifest.json" as i added
{ "name": "Medium Unlimited: Read paid content for free!", "description": "Unlocks medium.com for unlimited reads, no membership required", "short_name": "Medium Unlimited", "version": "1.5.0", "manifest_version": 2, "background": { "scripts": ["background.bundle.js"] }, "browser_action": { "default_icon": "static/logo_128.png", "default_title": "Unlock Medium.com Article" }, "content_scripts": [ { "matches": [ "https://medium.com/*", "https://*.medium.com/*", "https://towardsdatascience.com/*", "https://hackernoon.com/*", "https://medium.freecodecamp.org/*", "https://psiloveyou.xyz/*", "https://betterhumans.coach.me/*", "https://codeburst.io/*", "https://theascent.pub/*", "https://medium.mybridge.co/*", "https://uxdesign.cc/*", "https://levelup.gitconnected.com/*", "https://itnext.io/*", "https://entrepreneurshandbook.co/*", "https://proandroiddev.com/*", "https://blog.prototypr.io/*", "https://thebolditalic.com/*", "https://blog.usejournal.com/*", "https://blog.angularindepth.com/*", "https://blog.bitsrc.io/*", "https://blog.devartis.com/*", "https://blog.maddevs.io/*", "https://blog.getambassador.io/*", "https://uxplanet.org/*", "https://instagram-engineering.com/*", "https://calia.me/*", "https://productcoalition.com/*", "https://engineering.opsgenie.com/*", "https://android.jlelse.eu/*", "https://robinhood.engineering/*", "https://blog.hipolabs.com/*", "https://medium.muz.li/*", "https://ux.shopify.com/*" ], "js": ["main.bundle.js"] } ], "icons": { "16": "static/logo_16.png", "48": "static/logo_48.png", "128": "static/logo_128.png" }, "content_security_policy": "script-src 'self'; object-src 'self'", "permissions": [ "webRequest", "webRequestBlocking", "https://medium.com/*", "https://towardsdatascience.com/*", "https://hackernoon.com/*", "https://medium.freecodecamp.org/*", "https://psiloveyou.xyz/*", "https://betterhumans.coach.me/*", "https://codeburst.io/*", "https://theascent.pub/*", "https://*.medium.com/*", "https://medium.mybridge.co/*", "https://uxdesign.cc/*", "https://levelup.gitconnected.com/*", "https://itnext.io/*", "https://entrepreneurshandbook.co/*", "https://proandroiddev.com/*", "https://blog.prototypr.io/*", "https://thebolditalic.com/*", "https://blog.usejournal.com/*", "https://blog.angularindepth.com/*", "https://blog.bitsrc.io/*", "https://blog.devartis.com/*", "https://blog.maddevs.io/*", "https://blog.getambassador.io/*", "https://uxplanet.org/*", "https://instagram-engineering.com/*", "https://calia.me/*", "https://productcoalition.com/*", "https://engineering.opsgenie.com/*", "https://android.jlelse.eu/*", "https://robinhood.engineering/*", "https://blog.hipolabs.com/*", "https://medium.muz.li/*", "https://ux.shopify.com/*" ], "web_accessible_resources": ["static/*"] }
2- add sub-domain in 'background.bundle.js' as i do
var r = e(50), i = [ "https://medium.com/*", "https://www.google.com/search/*", "https://towardsdatascience.com/*", "https://hackernoon.com/*", "https://medium.freecodecamp.org/*", "https://psiloveyou.xyz/*", "https://betterhumans.coach.me/*", "https://codeburst.io/*", "https://theascent.pub/*", "https://*.medium.com/*", "https://medium.mybridge.co/*", "https://uxdesign.cc/*", "https://levelup.gitconnected.com/*", "https://itnext.io/*", "https://entrepreneurshandbook.co/*", "https://proandroiddev.com/*", "https://blog.prototypr.io/*", "https://thebolditalic.com/*", "https://blog.usejournal.com/*", "https://blog.angularindepth.com/*", "https://blog.bitsrc.io/*", "https://blog.devartis.com/*", "https://blog.maddevs.io/*", "https://blog.getambassador.io/*", "https://uxplanet.org/*", "https://instagram-engineering.com/*", "https://calia.me/*", "https://productcoalition.com/*", "https://engineering.opsgenie.com/*", "https://android.jlelse.eu/*", "https://robinhood.engineering/*", "https://blog.hipolabs.com/*", "https://medium.muz.li/*", "https://ux.shopify.com/*" ] }]);