Poco::MongoDB implements code to support all wire protocols.

However, old wire protocols were deprecated in version 5.0 and removed in MongoDB version 5.1 (current version is 8.0).

https://www.mongodb.com/docs/manual/legacy-opcodes/#std-label-wire-legacy-opcodes

New wire protocol (the OP_MSG protocol) is available since MongoDB 3.6.

Support for old wire protocols shall be removed from Poco::MongoDB as it is not available in any supported version anymore.