I have the same problem in my projects. Can't get Charles log now,but it is connected to the special advertisments. Most people had good experience, after reloading the app. But the issue can reoccur as the same or alike ad will be presented.
I think it is something connected to the size of the banner, as I read it somethere in the internet. There was a post several years ago. It was told, that banner can't get the right size to be shown and this points to an error or black screen.
Maybe the issue connected to the Smart or Adaptive banner size.
Unity 2018.4... most of them have the same issue.
Regards
Any version of Unity 2018.4.1, 2018.4.2, ... 2018.4.21
I didn't understand, should I create different thread with the same issue described? Why? I can see many bad notes in Google Play with the same issue described from Huaywei Mate users.
I don't have Huaiwei phone, so no Charles logs from my part. But I think your engineers team has such phones and there should be kind of debug app to check many ads inside banner placement to verify the issue.
Regards