My MBP 2018 13" i7 had to get its keyboard replaced a whole two days after I got it...a brand new work machine. That was in May 2019. Flash forward to two weeks ago, I noticed an occasional and very brief flicker, maybe about an inch above the bottom of the screen. It's not even the whole screen, just an inch or so of it.
Is it possible that the connector is just coming loose after the keyboard replacement? It has Apple Care and there's an Apple Store not far from my house, it's more the PITA of taking it in and having to use one of my own machines for a few days.