I do have an annual subscription. I am not using the 120 per minute or 4000 calls per hour. The dashboard shows 708 call this month, which I think reset about a week ago. So I should be well below being throttled.
I do have backoff logic installed if I get an initial rate limit error. if after 3 tries I also wait 30 minutes. When I get the errors it happens multiple 30 minute wait intervals. So I do think either my account is not getting properly recognized as yearly or there is a separate issue.