I'm going to disagree a little with Gadgetgeek. 21k miles per year doesn't indicate fast charging, it's just pretty average use 80 miles per day five days a week.
And I'm also going to say that fast charging isn't the enemy of EVs that you might think if you believe everything you read on the Internet.
The enemy is high state of charge, and high temperature.
The specific usage pattern of this used car we'll never know. But if you give an EV to someone on lease, that they basically don't care about because they're only keeping it 2 years, what are they going to do? The answer is make sure its always fully charged. They'd charge it whilst driving it if they could. Because the only question anyone asks them is 'how far can it go on a charge' and they have range anxiety.
So, instead of charging to 80% and discharging on their daily 80 mile commute to 40% then taking it back to 80%. They go to 100% every night, just in case. Even on Friday night, so the car can sit at 100% all weekend.
This is all guessing and supposition, but that is how to degrade an EV. Multiple consecutive DC charging did some damage to early Leafs and similar because they have no battery cooling... and they got hot. Not a problem with the MGs which have lovely glycol coolant circulating.
The worst EVs to buy are those ex demonstration models that have been literally on charge in the forecourt 24/7/365 with just the odd test drive around the block... then back up to 100%!!
You can't reverse degradation, but you can take care of your car from now on so ensure future degradation is as low as possible.
Regards,
Tom.