The thing is, many questions have been tagged files but were actually about files (the concept), not Files (the application).
What name should we keep? Tag names for applications and concepts raised this point already. It was inconclusive due to low views and voting, though the only opinion that was expressed was to use generic terms for the concepts (files about files) and prefixes for the applications (pantheon-files about Files).
Either way, please undo the synonym while we sort this out (this requires moderator intervention), then we can retag any files question that's about Files to pantheon-files. Then, if we decide to make files about files, a moderator can rename tags as desired.