Mine started since middle of last year just after my warranty expired.
The flickering first started when I was using it longer than usual, almost 12 hours continuously. Then I shut it off. The next day, I used it again and this time it appeared within 2 to 3 hours. Then the flicker will always start to appear after 2 to 3 hours and maybe longer if I use it in a super cool place. I read through the MS forum and decided not to contact the Customer Service. I live outside US so it is quite difficult to go for exchange if not refund. I tried disable Hyper V thing, Flu.x software, the task manager, the ticking clock and it only delay the appearance of the flickering. Updating software to the latest version is not a solution. I don't fresh install as I read it is not going to help either.
I am super disappointed with MS. Regret ever since as SP4 did not come cheap. I was eyeing for Surface Book 2 but this experience thought me not to trust MS product as yet. I need a replacement for my SP4 so maybe I am going for Dell XPS 13. I really hope MS will take responsibility on this issue (it might not happen though).
My spec: 128Gb, i5, 4Gb RAM
Link to my evidence