I see a few posts on here regarding concerns about StrictMode policy violations being reported in pre-launch reports - & in fact I had a bunch in a report for a new app that I released to my internal testing track.
Here's a link to the Android Developer documentation regarding StrictMode policy violations:
https://developer.android.com/reference/android/os/StrictMode
The upshot is that you don't need to be concerned about fixing every violation reported. StrictMode is more of a tool to help you find things that you might be doing by accident than a hard & fast indicator of an issue. It's worth having a quick read of the StrictMode documentation.
- Colin.