That is using the legacy call system or even a custom system and definitely not element-call. Its not compatible with element or element-x and doesnt support large calls.

Large group calls are an absolute must if you want anyone to adopt your protocol. Element call is fucking amazing. The performance is really good client and server side. You can easily do calls with 100 people, it has proper screensharing and muting support and works as a accountless standalone web app too.