Then you’ll have to find us better documentation on what exactly is being done.
The Powershell base64 value is clearly not directly based on the GUID hex value, even though there is some correlation:
>>> from base64 import b64decode
>>> from difflib import Differ
>>> from uuid import UUID
>>> from pprint import pprint
>>> def hexdiff(a, b):
... a = [format(v, '02x') for v in a]
... b = [format(v, '02x') for v in b]
... return Differ().compare(a, b)
...
>>> print(b64decode("e5kmfqkJbk+0BnNy46XDcA==").hex(), UUID('7e26997b-09a9-4f6e-b406-7327e3a5c370').hex, sep="\n")
7b99267ea9096e4fb4067372e3a5c370
7e26997b09a94f6eb4067327e3a5c370
>>> pprint(list(hexdiff(b64decode("e5kmfqkJbk+0BnNy46XDcA=="), UUID('7e26997b-09a9-4f6e-b406-7327e3a5c370').bytes)))
['+ 7e',
'+ 26',
'+ 99',
' 7b',
'+ 09',
'- 99',
'- 26',
'- 7e',
' a9',
'- 09',
'+ 4f',
' 6e',
'- 4f',
' b4',
' 06',
' 73',
'- 72',
'+ 27',
' e3',
' a5',
' c3',
' 70']