The reduce plugin that ships with TeXmacs 2.1.4 is no longer working on Apple Silicon computers as the plugin relies on Reduce PSL by calling redpsl.
The problem is, that due to severe memory handling issues PSL does not run on M1, M2, and M3 chips anymore –– and it will not do so in the foreseeable future. See the discussion on the Reduce developer’s forum. CSL Reduce (redcsl), however, is working fine on these new Macs.
A work-around to get Reduce running from within TeXmacs again is to locally install Eberhard Schruefer’s reduce plugin. It basically works out of the box by giving the user an option to launch redcsl. Other than that, the plugin seems to be offering the same functionality as the default one while avoiding some of the annoying typos in the menus.
The maintainers of the reduce plugin may consider incorporating/merging that functionality into the standard TeXmacs plugin.
Cheers, Tilda