ProxySettings.toString() includes the raw SOCKS5 proxy password. Since SocketSettings.toString() and MongoClientSettings.toString() embed it, and the sync, reactive-streams, and legacy drivers log the full settings at INFO on every MongoClient creation, the plaintext proxy password is written to application logs.
Fix: mask the password in ProxySettings.toString() (e.g. password=), matching the existing convention in MongoCredential.toString().