Hello,
This may vary depending on the client that you are using to RDP into the remote machine.
Some RDP clients may have functions such as "Right Click> Paste" or "Right Click> Take Control> Copy/Paste> Insert Password". But specifically in the native Windows RDP Client, the functionality has been disabled on purpose as specific here:
"Pasting the contents of the clipboard into a secure input box is intentionally blocked in Windows 10. However, the Consent.exe crash is a software problem."
One of the workaround would involve changing the behavior as documented in this article:
https://learn.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/user-account-control-switch-to-the-secure-desktop-when-prompting-for-elevation
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