Do you have the latest version of HWiNFO and Streamdeck plugin?
What system locale/language are you using?
Do you maybe have the "Use Unicode UTF-8 ..." option enabled in advanced Regional Settings of Windows?
Have you also restarted Windows after enabling UTF-8?
If yes, please try to change your Region in Windows to something else (e.g. USA) and restart HWiNFO if that will show correct degree character.