Hi Artem Kuznetsov , Welcome to Microsoft Q&A platform and thanks for posting your question here.
As I understand your issue, you are trying to copy data from Dataverse to Delta sink. However, you are getting unexpected results where the column values are not getting updated in the sink.
Kindly make sure in the sink settings, you have unchecked the 'Allow insert' checkbox and have selected either 'Allow update' or 'Allow upsert' option. You can set 'update if' policies using Alter row transformation .
For more details, kindly check the below resources: Alter row transformation in mapping data flow How to update sql table after performing data validation checks using mapping dataflow Alter row transformation Hope it helps. Kindly accept the answer if it's helpful. If it doesn't help resolve your issue, kindly revert back with your observations. Thankyou