What is it that WeChat group always automatically initiates real-time intercom?

That's because someone in the group started the real-time intercom. You can click Exit and close it.

Specific steps of real-time interphone shutdown:

1. After entering the real-time intercom state, click the arrow in the upper right corner to minimize the real-time intercom.

2. At this point, the real-time intercom is still on. Click on video chat.

3. After the pop-up window, click OK to close the real-time intercom and hang up the video chat.