Length of appids generated with calculateappid function differs from those generated internally by Steam

[aclist]

As a test (boiled down to the bare essentials):

import binascii
exepath = '"/some/path/to/game/game.exe"'
appname = 'game.exe'
appid = binascii.crc32(str.encode(exepath + appname)) | 0x80000000
print(appid)

The result is an 11-digit integer. When the same path and binary is supplied manually to Steam via Add a Non-Steam Game, the resulting appid is 21 digits long. (Steam-generated appid can be explored via shortcuts.vdf or by generating a desktop shortcut internally through Steam) Is there a reason for this discrepancy?

Using the 21-digit appids to directly launch user-defined apps via the Steam browser protocol works, but the ones generated with the function above do not. I ask because I intend to reuse a portion of the logic above in an unrelated application. Thanks.

[aclist]

Please disregard, seems the appid generated above is the base shortcut id and I needed to recalculate it to obtain the longer Big Picture id.