Coverage is not moving

I have built a custom serverless app and testing it before packing, but the code coverage is not moving beyond 56-58% though I don’t see any functionalities missing from the testing, also I do not have full control on simulating the test cases. I have also tried to remove the report.json from root folder, but it also did not help.

Please help me to get it packed. This is a custom app, so there is no impact on the product.