Hey,
I discovered the problem and found a rather brute solution to it.
I opened Activity Monitor and waited for the screen flickering to happen. That’s when I noticed that the WallpaperImageExtension process was causing the wallpaper to restart—it was failing to find a wallpaper in its cache. You can confirm this yourself by opening Console from the Applications folder. Set the filter to "Errors and Faults" and search for WallpaperImageExtension. Every time the flickering happens, you'll see an error log pop up in the filtered list:
Since it wasn’t possible to stop or disable this service alone (because it’s a child process of com.apple.wallpaper), I had to stop the entire wallpaper service. This means no wallpaper at all, unfortunately.
Here’s how to disable it:
1- Boot your Mac in Recovery Mode by shutting down and then pressing the power button until the options page appears.
2- Open Terminal from the Utilities menu bar.
3- Disable System Integrity Protection (SIP) by running this command:
csrutil disable
4- Restart and boot normally, then open Terminal and run this command to unload the wallpaper service:
launchctl unload /System/Library/LaunchAgents/com.apple.wallpaper.plist
This will stop the wallpaper from restarting until your next reboot or whenever you want to use a wallpaper again.
Note: It's generally not recommended to disable SIP, but if this bug is driving you crazy, it’s worth doing for some peace of mind. To re-enable SIP, just reboot into Recovery Mode and run:
csrutil enable
However, be aware that once SIP is re-enabled, the wallpaper service will start again, and you won’t be able to stop it without repeating the process.
