I will often get a response text from a friend that has an iPhone and the first few lines are replaced by this "Ԁ̭Ȃ" text followed by normal English words to finish the conversation.
Welcome to Android Central! Did you ever have an iPhone? If so, did you make sure your iMessage account was completely deactivated before switching to Android? Not doing so usually causes problems with messages from iPhone users not arriving at all, but I wonder if it might also cause text corruption like you're experiencing.