A dealer should be able to establish this. I’m not sure how you can check it yourself. From things that I have read, battery degradation at your stage of ownership is either because the BMS needs updating or it hasn’t been balanced properly (ie charged to 100% and left to go off on its own and not unplugged at 100%). In my experience, balancing can take 1-1.5 hours after the full charge. Rebalancing is either via a home normal plug socket (in the garage) or a 7kW one but not a rapid charger. i was always cautioned about rapid charging without regular balancing. In my Gen1 model I balanced regularly so that range wasn’t reduced because of inbalance.
Just fyi. I have also reached out to YouTube MG ZS EV video creators, such as Modern Heroes and Electric Vehicle Life who also were very helpful as well as the folk on here.
You havd 3 modes of driving - econ, normal and sport. You notice the deceleration with econ but I used it all the time.