Что не так с адресацией переменных в php?

<?php
$a['s'] = [
    ["name"=>"test1"],
    ["name"=>"test2"],
    ["name"=>"test3"],
    ];
foreach($a as $k=>&$v1){
    
}
$test = $a;
foreach($test['s'] as $k=>&$v2){
    if($v2['name'] == "test1"){
        $v2['value'] = "test4";
    }
}
echo '<pre>'.print_r($a,1).'</pre>';

Array
(
    [s] => Array
        (
            [0] => Array
                (
                    [name] => test1
                    [value] => test4
                )

            [1] => Array
                (
                    [name] => test2
                )

            [2] => Array
                (
                    [name] => test3
                )

        )

)

foreach($a as $k=>&$v1){
    
}