My AI product was fine at 100 users. At 1000 the OpenAI bill was 8x what I expected. Anyone else?

Been talking to a lot of founders building on AI APIs lately and the same two things keep coming up.

Cost spikes nobody predicted when they started scaling. And model quality quietly degrading because a version changed somewhere and nobody had monitoring set up to catch it.

Both problems discovered after users already felt them.

Have you personally run into either of these building on top of AI APIs? Cost surprises at scale or model quality dropping without warning?

Just trying to understand if this is widespread before I build anything around it.