The car is simply charged without any communication. It just has a completely normal connection for the socket. The way historic vehicles from the 20th century are charged.
We know this mode best from Schuko cables (ICCB). It describes a charging process in which the charging cable is practically mode 1 on one side and a control unit in the middle, which makes model 3 for the car on the other side. This control unit is also known colloquially as a brick. In addition to the type 2 protocol, it has other security properties and checks, for example, that the connector on the mode 1 side does not overheat.
That is the standard that we know best. Type 2 with standardized protocol. Every charging station and wallbox does just that.
Now we are talking about CCS fast charging, i.e. with DC power. No distinction is made between 400 V and 800 V.