The MG ZS EV uses a Bosch electric steering system and therefore COULD be using the Bosch brake I Booster system.
Below is a link to the Bosch web site, for anybody is interested in how the brakes are assisted in an electric car.
Half way down the page there is short video explaining / demonstrating how the system operates.
Vacuum is supplied by an electric motor that is constantly producing a vacuum to keep the servo reservoir top up.
The Tesla system works in a similar way.
Not too dissimilar to the servo unit used in an ICE car, but it this case the vacuum is provided by ICE.
When the reservoir is filled, even if the electric motor looses power, there should be enough stored vacuum to bring the car to a stop.
The iBooster is a vacuum-independent and electromechanical brake booster.
www.bosch-mobility.com