In my case, and I assume its the same for most folk who go to appeal is after the DWP make their decision you get a letter saying something along the lines of “your DLA/PIP will stop on ‘such and such date’” or if like me with my care allowance increasing from middle to higher rate but the mobility part going from higher rate to lower rate the letter just explains how much they will pay you in future for the award they gave you and for how long and of course giving you the good news that your car is going if you don’t get the higher rate.
Once you lodge your appeal all the payments that were set out in the outcome letter will continue but the extra money for higher rate mobility will stop.
If and when you win your appeal you will have a back payment from DWP back to the day they stopped paying you high rate mobility. The amount you get will depend on how long you kept your Motability car after losing higher rate but that’s a minefield of variations so can’t say anything certain on that as my case could be different from other cases because of the Motability transition handshake you get if you lose DLA that only counts if its a DLA to PIP transition and not a PIP to PIP transition.