Here is a relevant discussion at a popular Windows driver developer forum:
https://community.osr.com/t/locked-out-of-microsoft-partner-center-driver-submission-page
It is not clear whether this is a new Microsoft policy or just a problem on their portal. Either way it effectively locks out multiple 3rd party drivers from the Windows kernel. Even if a developer has a driver with a critical problem such as a crash or CVE they are no longer able to update their driver.
I am posting here to raise awareness on this issue. My hope is that this is not a new Microsoft policy and someone within Microsoft will realize there is a problem and fix it.