The problem here is that kernel drivers have to be signed and drivers will stop working if the signature expires because the vendor didn't use a time stamp server during the signing process. The drivers were clearly indended to keep working so I assume this happened by accident.

The big question is why on earth can drivers that have been verified and are already installed in your system can suddenly stop working? If this mechanism is intended to protect against malware disguised as drivers then it's already too late. The malware had several years to exploit your system.

Expiration after installation simply doesn't make sense for code signing. The signed executable won't change unlike a website. The driver is always going to have the same file hash, forever.