As per the Massive Text Embedding Benchmark (MTEB) Leaderboard maintained by Huggingface, OpenAI's embedding models are not the best.

https://huggingface.co/spaces/mteb/leaderboard

Of course, that's far from saying that they're the worst, or even headed that way. Just not the best (those would be a couple of fully opensource models, including those of the Instructor family, which we use at my workplace).