Works in CMD but doesn't work in Python?

Question

Python

Tell me why the request in Python may not work, it gives the error "the specified key or parameter in the registry cannot be found"
Python:

import subprocess

keyPath = "HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Authentication\\LogonUI"
output = subprocess.run(["reg","query",keyPath,"/v","LastLoggedOnDisplayName"])
print(output.stdout)

And if I enter the same query in cmd, then everything works and I get the result.
cmd:

reg query "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI" /v LastLoggedOnDisplayName

Answer 1

import subprocess

keyPath = r'HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI'
output = subprocess.run(
    ['reg', 'query', keyPath, '/reg:64', '/v', 'LastLoggedOnDisplayName'],
    stdout=subprocess.PIPE, stderr=subprocess.PIPE, encoding='cp866')
print('stdout:', output.stdout)
print('stderr:', output.stderr)

Answer 2

> Microsoft\Windows
backslash lost