I don’t know where to post launcher related bug reports, so i do it here.
i encountered this week a bug in epic launcher relating to plugins.
I don’t know what exactly lead to this, but i think the launcher isn’t deleting the whole plugin folder if a newer version of the plugin is available.
This happened to me with the DungeonArchitect plugin. I got a few older files (in different folders) which were not deleted (intermediate and source folder).
They even persisted uninstalling the plugin from the engine via the launcher.
My guess is, that you only operate over a file list, but if the plugin moves files from folder A to folder B they were not deleted. Possibly happened to me because i skipped a few releases of it, dunno for sure tho.
Fix should be easy, just clear the whole folder when updating/uninstalling/installing the plugin.
There should never be a leftover file, because this could lead to other (easily exploitable security related) issues.