I totally agreed with you, since Surface Pro 4 is a failed product, at least the issue is still unsolved.
Microsoft should either refund or upgrade at a reasonable price to Surface Pro 4 existing users, in order to re-gain their brand reputation and customer. I won't mind to upgrade if the new Surface Pro (5th) or Surface Laptop has no such problem.
Honestly, I did not recommend and also discourage my friends and family members when they ask my opinion on Microsoft product, software is okay, hardware is no, a BIG NO.
We have 3 Surface PRo 4 devices which all started with this issue within the last few weeks. Contacted Microsoft and they said that the y only replaced devices until April 2019 and now have to pay for a replacement of a device that has a known manufacturing defect!
Hallo, at first I thought I got helpful advice. The screen flickert only a little bit in the lower part. Microsoft chanced the pencil and the first run of the diagnostic toolkit seemed to help (I was in the 'three years'). The Surface seemed to be ok again.
so perhaps the things might help you.
But I have to say: The flickering came back after a few weeks. I did a lot of noting with drawboard pdf and onenote during work with the surface, it got hot (?) and it is worse than ever. I can not use the Surface anymore.