Upon upgrading to macOS Tahoe many users have experienced broken multiple monitor support, many have found that upgrading to the latest version may help or swapping out the cable may also fix the issue. However, before trying either run the following commands and reboot the system and it should fix the issue for most:
sudo rm -rf ~/Library/Preferences/com.apple.windowserver.displays.plist
sudo rm -rf ~/Library/Preferences/ByHost/com.apple.windowserver.*.plist
sudo rm -rf /Library/ColorSync/Profiles/Displays/*Once the commands have been executed, reboot your Mac and hopefully this should resolve the issue.
If the issue still persists, upgrade to the latest version of macOS Tahoe then try swapping the display cable.
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