The current release of Oxygen (<oXygen/> XML Editor 23.1, build 2021082307) is still shipping with the TEI 4.1.0 release from August 2020. The current TEI release is version 4.3.0. Last updated on 31st August 2021, so that's too new for this Oxygen release, but the previous one was Version 4.2.2. Last updated on 9th April 2021, which should have been included in Oxygen 23.1.
Is there a problem with the framework build process that prevented its inclusion? I'm working myself with the bleeding-edge plugin version, where everything is working fine as far as I can see, so I don't think there's anything that should be preventing the use of the current release.
Having trouble installing <oXygen/>? Got a bug to report? Post it all here.