Let's document srvMaxHosts in MongoClient options. So far the only mention of srvMaxHosts is in the changelog here:

MongoClient now accepts a URI and keyword argument srvMaxHosts that limits the number of mongos-like hosts a client will connect to. More specifically, when a mongodb+srv:// connection string resolves to more than srvMaxHosts number of hosts, the client will randomly choose a srvMaxHosts sized subset of hosts.

https://pymongo.readthedocs.io/en/stable/changelog.html?highlight=srvMaxHosts#notable-improvements