Dependencies in https://pypi.org/project/pymongo/ gave an example with:

python -m pip install "pymongo[gssapi,aws,ocsp,snappy,srv,tls,zstd,encryption]

Attempting to install PyMongo 4.2 with pymongo[ocsp,srv,tls] resulted in a warning:

WARNING: pymongo 4.2.0 does not provide the extra 'tls'

I assume the "tls" extra was from a previous version and no longer optional.