Hi@akashsaraswat19,
Based on the issue that you mentioned, I discovered that you have proposed a similar case which has been marked solved. Is there anything unsolved, could you please share more about your scenario?
We are used to using LookUp() when it comes to auto-populating one field based on another field filled. This function is easier and efficient.
Since you mentioned that this autofill issue is related to submitting a new form, I think there is something different from the case you proposed before.
I have a test on my side, you can take a try as below.
Set the Default property of the data card belonging to product name as below
If(EditForm1.Mode=FormMode.New,LookUp(Employees,EmployeesId=DataCardValue3.Text,EmployeesName))​
On your side, you can write as below
If(EditForm1.Mode=FormMode.New,LookUp(Table1,ItemNumber=DataCardValue3.Text,ProductName))​
Note: DataCardValue3 represents by the control belonging to Item Numbers in your Form.
You can also check the GIF attachment for reference.
Best Regards,
Qi