If the default value for encoding is not passed it will be "base64":
https://github.com/openai/openai-python/blob/main/src/openai/resources/embeddings.py#L95
but the documentation says it will be "float":
https://platform.openai.com/docs/api-reference/embeddings/create#embeddings-create-encoding_format
(Not allowed to add links to topic sorry)