Hi @Ahmad Nowfal khan ,
According to the document below, Outlook supports syncing drafts across devices for specific account types:
Does your app support draft syncing?
So, it appears to be any expected behavior at present if your mailbox is hosted on Exchange on-premises like Exchange 2016 or Exchange 2019. If this cannot explain your situation or you need further help on this, please understand that the "Microsoft Exchange Hybrid Management" tag is for general questions about Exchange Hybrid, for questions involving Outlook mobile devices, you may visit the dedicated forum for Outlook mobile app:
https://answers.microsoft.com/en-us/outlook_com/forum/outlk_mob
Thanks for your understanding.
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