In https://pymongo.readthedocs.io/en/4.4.0/examples/encryption.html#explicit-queryable-encryption the following comment doesn't seem to refer to anything in the actual code:
> The value of "data_key_id" must be the same as used to encrypt the values above.

"data_key_id" should be "indexed_key_id".

Thanks jmikola@mongodb.com for pointing this out.