Windows 11 Global folder icon registry tweak hidden drawbacks

The Shell Icons registry override is a substitution, not Microsoft’s documented per-folder method. It can affect File Explorer, desktop views, file dialogs, and applications requesting the same icon index. An invalid path or resource index may create blank icons, while cache rebuilding, Windows updates, or third-party shell software can make results inconsistent.
It normally changes presentation rather than folder contents, permissions, or file operations, but treat it as unsupported customization. Export the affected key, keep the icon in a permanent local path, record the original values, and test with a separate profile before wider deployment.
For individual folders, use Properties > Customize where available, or Desktop.ini with a ShellClassInfo section and IconFile or IconResource setting. That limits the blast radius. If you retain the global override, test Explorer, Open and Save dialogs, OneDrive locations, and special folders after updates. Keep a rollback plan because an update may reset the mapping.