The API key was not accepted

The key is missing, mistyped, unknown, revoked or expired. Every one of those gets this same answer, so an error never tells a stranger which keys are real.

What to do

Send Authorization: Bearer <key> with a key from the console's API keys page. A rotated key's old secret stops working when its overlap ends.

Retrying

No: the same request gets the same answer until something is changed.