Try reporting czc.cz using the "report" link in extension's menu: you'll see I'm aware of the problem and it will be fixed soon. Btw, you don't have to uninstall the extension just because of that: you can whitelist that website until it has been fixed.

Asus.com will work soon. When you're on that site, please use the "report" link in extension's menu (next to the address bar usually) - you'll see then that I have already checked it and prepared a fix :)

It used to (and still could) work in regular Firefox for Android but Mozilla team decided to stop supporting all extensions (they now allow only a couple of handpicked extensions).

It works in "Firefox Nightly" though, but the installation procedure is a bit complicated. I tried it and it works well: https://blog.mozilla.org/addons/2020/09/29/expanded-extension-support-in-firefox-for-android-nightly/