coconutBattery Plus (premium version) vs Apple Genius Bar Support Tool differ significantly

Since the iPad iOS does not report battery health like iPhone iOS, you need to use a third party tool because Apple does not give out their diagnostic tool to end users. So I purchased coconutBattery plus version 3.9.10, which is the latest version as of 1/14/2023 to assess the current battery capacity of my devices.

I used CoconutBattery on two of my iPads and also brought them into the Apple Store with an appointment to assess the battery health. If the battery health is <= 80%, they will replace each iPad at a cost of $99 as of 1/14/2023. Note: Apple plans on increasing the price in effective March 1st, 2023.

CoconutBattery battery health was significantly different than Apple diagnostics battery health. as shown below:

• iPad Pro 10.5in 2nd Gen 2017
  • Full Charge Capacity = 5384 mAh
  • Design Capacity = 8134 mAh
  • Design Capacity % = 66.2%
  • From History:
    • Maximum Capacity = 5224 mAh
    • Health=64.2%
  • Apple Diagnostics Tool: Health 77%
• iPad Pro 12.9in 2nd Gen 2017
  • Full Charge Capacity = 8257 mAh
  • Design Capacity = 10875 mAh
  • Design Capacity % = 75.9
  • From History:
    • Maximum Capacity = 8607 mAh
    • Health=79.1%
  • Apple Diagnostics Tool: Health 85%

First, CoconutBattery is a confusing as it has two health percentages, one calculated from the Design Capacity and the other from the Maximum Capacity values. The Design Capacity mAh value is seem from the iOS Device Menu, but the Maximum Capacity mAh value is shown in the History. Since the Design Capacity value and the Maximum Capacity value differ for the same device and date evaluated, I'm not sure which one to actually use when comparing with the Apple Diagnostic health value. For the purpose of this question, let's use the Maximum Capacity health value to compare with the Apple Diagnostic Tool results.

Secondly, the value of the Maximum Capacity Health from CoconutBattery significantly differs from the Apple Diagnostic results.

       Device         CoconutBattery   Apple Diagnostic    Difference
iPad Pro 10.5in 2017       64%              77%               13%   
iPad Pro 12.9in 2017       79%              85%                6%

Why such a huge discrepancy? So, I can get a battery replacement for the 10.5in iPad Pro, but not the 12.9in iPad Pro until it is at or below 80% battery health. It's kind of annoying with the different values and making trips to the Apple Store only to find that I need to wait for another few months......

Looking for anyone to provide feedback and ideally an answer to the questions aforementioned above.

Thanks!