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<?php $emails = [ (object) ['email' => 'a'], (object) ['email' => 'b'], (object) ['email' => 'c'] ]; $userEmails = [ (object) ['user_email' => 'c'], (object) ['user_email' => 'a'], (object) ['user_email' => 'd'] ]; var_export( array_udiff( $emails, $userEmails, fn($a, $b) => ($a->email ?? $a->user_email) <=> ($b->email ?? $b->user_email) ) );
Output for 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
array ( 1 => (object) array( 'email' => 'b', ), )

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