Google AI Studio APIs and Billing Tier suddenly showing "Unavailable"

I’m experiencing an unexpected issue with Google AI Studio. All the API keys I previously created are currently showing their status as “Unavailable”.

Additionally, I checked my project settings and noticed that the Billing Tier is also listed as “Unavailable”. Just yesterday, my project was on the normal “Free tier”, and it suddenly changed today.

Has anyone encountered this issue recently? Is this a known system bug, or is there a specific step I need to take to restore my access? Any help or guidance would be greatly appreciated!