Happened only in windowed mode.
If I'm playing and then press esc, then go to view my achievements, then click on the wax on, wax off achievement (only one I have left) then go back, then back again and into the game, the game starts to flicker, all the way to the main menu.
I have to restart the game to fix it.
Thank you for your report!
We're tracking this issue in MCPE-130171, so this ticket is being resolved and linked as a duplicate.
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