@eieio_31310 
Thank you. I use android and google play games, I hope it's enough. I also screenshot my plants and my resources every once in a while (yeah, those are a lot of screenshots), but I'm not sure if it actually helps at all, lol. I don't think I can attach lots of images to EA Help Center (which is hopefully not necessary). I wonder if we can somehow have a back up of our own. Like maybe there's a save file/folder somewhere that we can copy paste as back ups.
On another note, it seems to have fixed itself somehow, thankfully.
@MAGICDAVESHROOM 
Phew, so I'm not the only one. I've only encountered this problem today, and it's not like it comes and goes, but in every play (and curiously, didn't happen with the Zomboss level).
Anyway, for some reason, after several consecutive plays force closed the game, now it has been back to normal just some time ago. I think I waited for a while after completing the game (with the ZPS reward display), before I tap on Continue to get back to the Penny's page. And it didn't force close, and it didn't happen again in the next plays after that one waiting.