You and users can click “Do not show me this dialog” again checkbox, which will set a setting in WebApp.
But you don’t want to see this dialog at all and there is no clean way to do this. Either inject the setting in webapp or
raise the version in https://stash.kopano.io/projects/KWA/repos/web-meetings/browse/webapp/plugins/spreedwebrtc/js/SpreedWebRTCPlugin.js?at=7295a1849f207c2b7c3ad2bb1cbb4c24f6473207#11
so it don’t correspond with the installed version.
But you could also disable the webmeetings plugin when it’s not correctly setup yet :-)