It is a quirk of MGs that when you reset the GOM it comes back with an unrealistic range figure, that very quickly then adjusts to a smaller range as you drive.
My Born doesn't do this and a relatives Mégane doesn't either, it may add 2/3 more miles but stays pretty accurate.
It is another quirk of the MG that it doesn't show lower than 2 Mi/kwh even though it is lower, this seems to be a thing across the range as Bjorn Nyland noticed it in the IM6 he had a shot of.
Again doesn't happen with the other 2 EVs I have access to, they will show under 2.