Have a visit here:
https://platform.openai.com/settings/organization/limits
See if you are tier-1 (by having paid OpenAI less than the required $50 in multiple payments).
Observe then the token rate limit for the model of 30000 tokens per second. Reduced ten-fold a month ago.
Attempting to send more tokens than that in a single request or per minute will result in an API error.
Assistants is unaware of your tier, maintains and re-sending long conversations to the model which can accept 128k, and makes multiple iterative calls to AI models without waiting, some of which are sending tens of thousands of tokens returned by a file search on documents. A single user question can fail. An entire thread can be rendered non-functional.