This is not a known issue! Is it during the ad? If so, it might be that your connection is too weak and the ad is not running well. I suggest checking with a stable WiFi connection and with your device up to date and coming back if the issue persists.
I’m still having problems when I watch an ad for Amazon. It freezes and I have to exit the game and come back. It DOES NOT happen with any other ads. It’s not my WiFi.
I've seen this issue on other games and it's something the game team can't fix as it has to do with a 3rd party provider.
What I do know is that they are investigating this so they are working on improving it but, it's not a priority at the moment as this feature is still being tested and it's also not available for all players.
My recommendation is to skip watching the video if you don't want to leave the game app and start it again and make sure your game app is always up to date.
I know this is not ideal, however, hopefully, boosters that you get rewarded in the game will help you out on those tricky levels