I have had this problem a lot since the mention upgrade. The computer has now been in for an annoying keyboard change and they have tested everything whilst doing this.
I have cooped with the error by just restarting the computer and that has been enough. I have also turned automatically adjust brightness off. The new devices from apple are really sensitive. I wished that I had got the older model MacBook Pro and not the one with butterfly keyboard. However the keyboard that was faulty has been replaced and I hope that never happens again.
I also punched a new iPhone X last month and that one has got microphone issues. I wonder if apple is running to fast with development and should need longer test periods?
Anyway if the flickering is a bug I hope they fix this promptly.
Good luck with this and hope it works out.
Kindest,