What does "mitigation" mean? Does it have a specific meaning in legalease?
You shouldn't let the car sit at over 90%. If you aren't driving anywhere soon, I'd use the app to set the climate control to high and open the sunroof. The battery should be down to 90% in an hour or so (well, assuming it's cold/cloudy enough for the heat to run; I've only used this trick in the winter).
Mitigation means they're willing to admit to what they did and offer a compromise solution. It could be as insulting as "we took 30 miles but if you let this go we won't take the rest" or it could be an honest "we can't afford to fix this for everyone now, but think we can within 5 years, would a cap right now and an offer of reparations over time be acceptable? We anticipate batter batteries eventually so people fixed now will get 18650 but people who can wait years will get lighter, faster charging replacements with more range or power."
It will probably be somewhere in between these unrealistic extreme examples and it will probably not be an acceptable offer initially.