Sending and receiving short messages that suddenly appear on mobile phones are connected by symbols. How can we eliminate it?

This is the short message symbol service opened by China Unicom. At first I thought I was poisoned. Please call customer service and ask them to cancel it for you. . . . It will also change the symbol according to what you send. . Like good night. . With the logo of zzzzzzzz. . Say hehe and you will have a smiling face or something. . .