Hi @Amit Dimri ,
Thank you for posting in the Q&A forum.
I can reproduce this behavior in my SharePoint Oline. It seems to be the default behavior for SharePoint Online since it happens in all document libraries on all sites, which is not fixable from our end. I have also tried using PowerShell to set this field as Read Only, but it does not work for this field either. I am a bit regretful that I was not able to help you much on this.
We recommend you give suggestion in the feedback portal and help to make improvements. Many features of current products are designed and upgraded based on customers’ feedback.
Thanks for your understanding.
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