Reproduction steps:
1) Open attached project "FlickeringUITest"
2) Open scene "MainScene"
3) Make sure you can see both Scene window and Game window
4) Enter play mode
5) In game view click and scroll the horizontal row of images
--- You should see that images start to flicker, as if sprites are being replaced for a moment
--- Sometimes flickering is visible in the Scene window and sometimes in the Game window
--- See attached video

Alternative reproduction project is available in duplicate case 773684
https://www.youtube.com/watch?v=wuA7cQUvHM8

Regression introduced between 5.3.2p1 and 5.3.2p4