HasComputedColumnSql() method not working as Expected

Question

I have configured the updatedAt property as shown below. I expected that the updatedAt value of the corresponding row alone will change when inserting or updating. But when tried this it is updating entire column i.e all the rows of the UpdatedAt are getting changed which is not expected.

Am I doing any wrong configuration or it is the expected behavior.

modelbuilder.Entity<Author>()
            .Property(a => a.UpdatedAt)
            .HasComputedColumnSql("GetUtcDate()");