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<?php $arr = [ '1' => (object) [ '2' => (object) ['1' => '1',], ], ]; array_walk_recursive($arr, function (&$item) { if (is_object($item)) $item = (array)$item; }); print_r($arr);
Output for 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
Array ( [1] => Array ( [2] => stdClass Object ( [1] => 1 ) ) )

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