hello AChSimba
Im Juliet and Im happy to help you :)
It's important to keep in mind that untested experimental features like "edge://flags/#edge-syd-chat" could result in unexpected behavior or problems. The "wallpaperList" file might have been created as a result of this function being enabled, but it was not automatically deleted when the option was disabled.
I would suggest you first try to manually remove the "wallpaperList" file to fix this problem. You can do this by finding the file in the Edge folder on your computer, which is often found in "C:\Users[your username]\AppData\Local\Microsoft\Edge"). If you delete this file, Edge's customized wallpapers and themes can also disappear.
You may need to conduct additional troubleshooting by looking through your browser's settings or extensions for any potential causes if the file keeps being produced even after being deleted.
I hope this helps. :)