When I open https://developer.apple.com/developer-id/ and click kext to sign the link(
To generate a Developer ID certificate and to submit your apps to be notarized, you need to be a member of the Apple Developer Program.
If you need to sign a Kernel extension with a Developer ID certificate, let us know.
), the web page is back to https://developer.apple.com/developer-id/.
I think it should jump to the application interface, then fill in the information and submit it to apple.