There may be several reasons why your iPhone 12 mini wireless charging can't be charged to 82 percent of the charge, please try the following solution:
1. Clean the charger and phone. Dust or debris may be blocking the charging port or wireless charger.
2. Replace a different charger or charging cable. Sometimes the charging cable or charger is incompatible or damaged, causing the charging to slow down.
3. Reset the iPhone 12 mini. Find \"General\" in Settings > \"Reset\" > \"Reset all content and Settings\" option.
4. Check the battery health status. In \"Settings\" > \"Battery\" > In Battery Health, view the health status of the battery.
5. If the above methods do not solve the problem, it is recommended to take your iPhone 12 mini to an Apple authorized repair station for repair or battery replacement.
It may be the charging protection function of the mobile phone, you can wait for a period of time to charge again, if you still can't rush into the electricity may be the battery or charger is wrong, you can go to the after-sales service to see if you can change the repair