What happened
Transcription requests share one queue across every organization, so each organization may have a limited number open at once, and make a limited number in any 24 hours. Thedetail states both counts and both limits.
You are not charged for the refused request. Repeating a request you already made never counts against either limit.
How to fix
Retry after theRetry-After header’s seconds. GET /v1/podcasts/transcription returns your limits, how much of each you have used, and when the oldest request in the 24-hour window leaves it, so you can pace a backlog of requests to stay under them.