In perl 5, values and variables are rather mushed together. The short answer is that that the object reference's referent, be it an array, hash, or scalar, is blessed into a package. This SV-like thing (as it may be an AV, HV, CV, or GV (the latter two if you're getting really weird)) has a little note tacked onto it saying that it's now an object, and marking the package the object belongs to.

When you assign to the entire array/hash/scalar that is your object, perl doesn't generate a new array/hash/scalar--it cleans it out and reuses it, including any blessing on it. (Yes, in some circumstances magic is removed. This isn't one of them)

You can check this with this little snippet:

$foo = \%bar;
print $foo, "\n";
%bar = ();
$foo = \%bar;
print $foo, "\n";
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which produces the output

HASH(0x80d0b84)
HASH(0x80d0b84)

showing that %bar hasn't moved. (And is, therefore, the same variable)