Running `strings` on the installation plugin (CWSPkgPlugin.bundle) shows why - it's using a similar process to what Zoom does [1]

  +[CWSUtilBase unzip:to:]
  /usr/bin/unzip
  Clean up temp unziped app done: %i
  unzip:to:
  [...]
  Cisco Webex pkg plugin, begin init work.
  Install CWS result: %i
  Launch CWS result: %i
  Terminate installer: %@
  Terminate self: %@
  [...]
  /usr/sbin/lsof
  forceTerminate

[1] https://www.imore.com/zooms-preinstallation-script-workaroun...