Receiving Chinese blocks of texts in the Messaging app

My wife is getting some weird text messages as replies in middle of conversations with her friends. The messages are blocks of Chinese characters. She gets these in the stock messaging app from friends that use Samsung phones and iPhones. She is using a Nexus 5X on AT&T. (**N.B.** Other users have asked the same question about the Samsung Galaxy S7, so it's not a phone-specific issue.) Here is a screencap from today from an iPhone user, and translating the text does not make sense (though I did image translation): : (Click to see the image in full size) --- Here is one from a Samsung phone and from their end: (Click to see the image in full size) Does anyone know why this is happening? Is it some weird thing when someone with a weird texting app replies with some emoji/GIF/image?