Hi,
Thank you for posting your query. According to your description, you want to stop spawing during RDP to a specific app. Via research, here is an official document may help you slove this problem.
Remote Desktop or RemoteApp session does not terminate due to spawned splwow64.exe process
https://learn.microsoft.com/en-us/troubleshoot/windows-server/remote/rd-or-remoteapp-session-not-terminate
Best Regards,
Grace
---If the suggestions above are helpful, please ACCEPT ANSWER. Really appreciate. This will also help others with similar issue to find this post quickly. ---