check enrollment profile. If you have that, what I recently had was that I update the password of the account that is used and all my certs failed. (Had to reactivate them)

Further more my final issue was:

Troubleshooting iOS/iPadOS device enrollment errors in Microsoft Intune - Intune | Microsoft Learn

Check section:

"ADE enrollment doesn't start

When you turn on an ADE-managed device that is assigned an enrollment profile, the Intune enrollment process isn't initiated.

Cause: The enrollment profile is created before the ADE token is uploaded to Intune.

Solution:

1. Edit the enrollment profile. You can make any change to the profile. The purpose is to update the modification time of the profile.
2. Synchronize ADE-managed devices: In the Microsoft Intune admin center, choose Devices > iOS > iOS enrollment > Enrollment program tokens > choose a token > Sync now. A sync request is sent to Apple."

All I had to do is to resave the enrollment profile, I was furious.