If you click on the Happy New Year message from an unknown sender (I should have known better), the message displays fireworks on my Simple watch face, and disappears from Messages. I figured it was from my wife.
Googling this issue, it seems that similar messages for New Years have been associated with covertly installing malware used to siphon data (Contacts, passwords, etc) from accounts. Erasing all content and settings from my apple watch and iPhone have not helped - the message reappears when I restore the watch from a pre-new-years-day backup... and appears to open automatically by itself.
Any help permanently removing this would be much appreciated.