Hi @Kuldeep Raj Tiwari,
As per my knowledge, it is an expected behavior when converting Excel to PDF using Graph API. This is by default and I'm afraid currently we cannot change this.
I would suggest you modify the change the format of the Date and Time fields to Text. Also, you can post feedback in this dedicated community to Graph API: https://feedbackportal.microsoft.com/feedback/forum/ebe2edae-97d1-ec11-a7b5-0022481f3c80.
Thanks:)
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