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...