Connections from kicked players remain active until they click OK themselves.
Only then is the ICE adapter of the kicked player closed and the connections to the players in the lobby disconnected.

This is not a visual bug, as the traffic can be traced with Wireshark.

Is it possible to automatically close the ICE adapter of the kicked client when the host kicks them?

51.38.36.80 is the VPN IP I use.

Possible connections or just placebo:
There is a belief that you have to manually kick all observers as the host before starting a game, because if you automatically kick the existing observers (start game (Launch) -> autokick obs), the host will experience a client crash (sometimes).
I've experienced this myself. But the question is whether it's just coincidence or a real bug.

If we consider this in relation to the initial topic, connections are only disconnected when the kicked observers close their ForgedAlliance.exe, thereby closing the ice adapter.
And everyone is familiar with the problems that arise in-game when players leave a match in progress, as this often disrupts connections (lag).
Assuming that auto-kicked observers only close the game on their own a few minutes after the game has started (because they are AFK or for other reasons), could this affect the ongoing game and break the connections?
Unless the host crashes at the start of the game cough...

Is there an option to prevent observers (all slots are occupied and a player tries to connect but is prevented from doing so -> game is full)?
Is it possible to implement something like this?

Thanks again to @Mettler0618 for helping with the testing.
Traffic continued. Only when the game was closed by Mettler0618 did traffic stop:

Btw: Something else I've noticed since I started using the ICE Adapter Debugger.
The connections displayed in the lobby don't match what the ICE Adapter Debugger shows.
In other words: the debugger shows “Connected,” but in the lobby you see the typical “Connecting...” message for the corresponding player.
I'm going to trust the debugger more than the lobby display.
But the host can't start the game here.
So: Not really connected or a bug in the lobby server (which has outdated connection data?) and therefore won't let the game start?