The flag no longer selects between an old and new plugin-command path; that path now runs unconditionally. The flag, which defaults to true, instead decides whether plugin and marketplace helper commands run at all, and turning it off skips them with the reason "disabled by the plugin command kill switch".
disabled by the plugin command kill switch
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
tengu_plugin_command_source_refresh Not enough to sayNothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.
This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.238: on
Read once, for one account on one subscription tier, against v2.1.238. It isn't a statement about your account. What a flag value here can and cannot tell you