if you have HDR or 10-bit pixel format enabled, please disable it in Windows display settings or in the graphics adapter (e.g. Nvidia or AMD) control panel.
Both features are not supported by spacedesk.
For further details, please refer to our user manual topic “Windows 11/10 Known Issues and Unsupported Features” (https://manual.spacedesk.net/Windows1110KnownIssuesandUnsuppo.html).