b64decode

Decode the Base64 encoded bytes-like object or ASCII string s.

Optional altchars must be a bytes-like object or ASCII string of length 2
which specifies the alternative alphabet used instead of the '+' and '/'
characters.

If padded is false, padding in input is not required.

The result is returned as a bytes object.  A binascii.Error is raised if
s is incorrectly padded.

If ignorechars is specified, it should be a byte string containing
characters to ignore from the input.  The default value of validate is
True if ignorechars is specified, False otherwise.

If validate is false, characters that are neither in the normal base-64
alphabet nor the alternative alphabet are discarded prior to the
padding check.  If validate is true, these non-alphabet characters in
the input result in a binascii.Error if they are not in ignorechars.
For more information about the strict base64 check, see:

https://docs.python.org/3.11/library/binascii.html#binascii.a2b_base64