The option name "keyspace" is misleading and isn't actually the keyspace. It's just some internal hashcat number.
Or to quote the FAQ entry you linked:
The part about how the hashcat "keyspace" is calculated is probably wrong.
Or to quote the FAQ entry you linked:
Quote:hashcat's --keyspace is specifically designed to optimize distribution of work, and is not a literal representation of the total possible keyspace for a given attack.
The part about how the hashcat "keyspace" is calculated is probably wrong.