Persona version is a little different from other plugins, it is fixed to your version of NodeBB. If you update your NodeBB, you should also get the newer Persona version.
@attis Thanks for debugging, I added a new config setting into config.json, you can set isCluster: true in your config.json and it should work now. It will be available in 1.9.2 so you can keep your change until then. https://github.com/NodeBB/NodeBB/issues/6509
These are warning messages meant for developers. You can safely ignore them. We try to minimize the amount of warnings shown due to these deprecations. Odds are they are just old requests from browser caches, or some other external cause.