Hi @parwaze sadool ,
This is OOB behavior when using Today() in SharePoint column validation.
When we update the item on a different date, no matter what column you edit, it will check the "Today()” verification and ask us to update the value to meet the validation.
If you don’t want the value to be changed once other column values change, we suggest you remove column validation and set default value for this column with Today’s date.
Try as follows:
Click “Claim_Reserved_on” column and select Column settings to choose Edit->Select Today’s date under Default value.
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