DWM.EXE High CPU (One Core) On Target System after Remote Desktop Disconnect on Windows 10 x64 1903 (Fully Patched)
As a workaround on all of my affected machines I have used Group Policy Editor to set:-
Local Computer Policy
Remote Desktop Service
Remote Desktop Session Host
Remote Session Environment
Use WDDM graphics display driver for Remote Desktop Connections to DISABLED
This forces RDP to use the old (and now deprecated XDDM drivers). After rebooting, behaviour returns to normal and after disconnecting from an RDP session the RDP host (target machine) no longer shows DWM.EXE consuming CPU.