There's nothing to patch, scanning is not possible.
It's either the extension's choice to become detectable ("externally_connectable" is off by default) or it makes unique changes to websites that allow for its detection.
It's either the extension's choice to become detectable ("externally_connectable" is off by default) or it makes unique changes to websites that allow for its detection.
All of these are opt-in by the extensions and MV3 actually force you to specify which domains can access your extension. So, again, each extension must explicitly allow the web to find it.