Quota limit reached for Claude Sonnet despite having Google AI Pro plan

I’m getting the following message:

“You have reached the quota limit for Claude Sonnet 4.5 (Thinking). You can resume using this model at 03/02/2026, 11:43:39. You can upgrade to the Google AI Ultra plan to receive the highest rate limits.”

However, I already have a Google AI Pro plan, so I’m not sure why I’m still hitting this quota.
Could you clarify why this is happening or whether this is expected behavior?