Normally in the new shop when you hit enter, you now go to a search function. If you start chatting with someone, then open the shop without sending your message and then keep typing, the client will freak out and eventually stop typing letters in the chatbox and instead starting acting like you're pressing hotkeys assigned to whatever you're typing.
Steps the recreate:
1. Open chat
2. Open shop
3. Click back into your chatbox
4. Start typing