Hi @Prince Ezeala ,
This seems to be an expected behavior. For Deleted Items, which is a special folder, the retention age is calculated differently for items that are in the Deleted Items folder and items that are not in the Deleted Items folder,as explained at How retention age is calculated in Exchange Online | Microsoft Learn
Here is a similar case for your reference:Retention policy to delete items older than 30 days in "Deleted items" folder - Microsoft Q&A
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