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<?php $buffer = [ [ 'test' => '1', 'test1' => '2', ], [ 'test' => '3', 'test1' => '4', ] ]; var_dump( array_merge(...$buffer), );
Output for 8.1.0 - 8.1.31, 8.2.0 - 8.2.27, 8.3.0 - 8.3.15, 8.4.1 - 8.4.2
array(2) { ["test"]=> string(1) "3" ["test1"]=> string(1) "4" }

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