The “blue-line” issue in W365 Cloud PC sessions usually points to a graphics rendering hiccup, often tied to display drivers or session rendering settings. A couple of things that help: make sure the host device’s GPU drivers are fully up to date, and confirm that the Cloud PC is running the latest Windows updates. You can also toggle the graphics acceleration setting in the Remote Desktop client turning it off has cleared this for some users. Another preventive step is to check network stability, since intermittent bandwidth drops can cause odd rendering artifacts. If the problem persists, re-provisioning the Cloud PC session sometimes clears out lingering config issues.
Give those a try, and if this resolves the glitch, please hit “Accept Answer” so others know it worked