it's not $blake2$ signature but $BLAKE2$
just try the example and see what happens.
put the hash in a hash file, because depending on your operating system and shell $variable like $BLAKE2 will be interpreted as a variable by your command prompt/cmd/shell/bash, if you do not escape it.
the problem is that rules need to be respected, otherwise there are always excuses: "it's just a hash of a friend", "it's just my neighboors wifi", "it's just millions of hashes of a friendly forum" etc... it's forbidden, for good reasons (if we do not stick to the rules, there will be always shady and absurd excuses)
just try the example and see what happens.
put the hash in a hash file, because depending on your operating system and shell $variable like $BLAKE2 will be interpreted as a variable by your command prompt/cmd/shell/bash, if you do not escape it.
the problem is that rules need to be respected, otherwise there are always excuses: "it's just a hash of a friend", "it's just my neighboors wifi", "it's just millions of hashes of a friendly forum" etc... it's forbidden, for good reasons (if we do not stick to the rules, there will be always shady and absurd excuses)