Could you please try to update your Intel(R) UHD Graphics 600 graphics driver from their website.
Or via Intel Support Assistant
If the issue still persist after GPU update, please download the spacedesk diagnostic script here, then extract it.
Inside you will find spacedeskDiagnosticTool.cmd, just right-click it then run as administrator.
This script will start a debug view app to capture spacedesk debug traces.
On step 5 it will prompt you to reproduce the issue (by connecting the viewer app and wait the viewer to show the image issue), make sure to do this before pressing any key to continue.
After the script is done, a folder will be created on the same folder as the script file which contains various log files that we need for analysis.
Please right-click it -> Send to -> Compressed (zipped) folder, then attach the *.zip file on your next reply.