Zoe battery

Hi EV users.
Does anyone have any knowledge about the traction battery efficiency on a Zoe. At me service last week, the battery was calculated at 89%.
Sounds ok, but l am sure last year it was a lot less.
In December ( after the service), my Zoe was off the road, and eventually after 6 weeks the fault was corrected. A totally new computer, and new charging point. Would a new computer alter the battery efficiency rating???

The firmware can get different readings. But just as likely to be the temperature. Poor capacity when cold then when warm.