how can i make this work (dont work)

Individual hash (and array) elements must be scalars. In order to store a more complex data structure, you have to store a reference — which is what $value already is. So assuming that this is what you want to do, and assuming %temp was previously declared as a hash,

$certname = $value->{'certname'};
$temp{$certname} = $value;
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should do the trick.