You need a valid reason to end your 3yr lease early – there are numerous valid reasons from cost of living to loosing your licence
There is not mutch info on Mb, but I wouldn’t expect there to be. Used car prices are still much higher than they should, so I doubt they would be bothered if you end the lease 4 months early.
https://www.motability.co.uk/get-support/faqs/cancel-lease-or-return-vehicle-early/