Forgot to update you there, we landed a proper fix last week at https://github.com/discourse/discourse/commit/499472b6a0e9bd0cef4539287e9845476938cf01
This was a Chrome 77 change, and is triggered if a Discourse tab is inactive (in background or using another app in Android) for more than 5 minutes.
Chrome pushed this new API for Android for now, but it will be pushed for all platforms in new updates.