Automatic seek on an index on a calculated column
You’re basically adding a helper-predicate, and that’s not something the SQL engine will do out of the box most of the time. It does for LIKE, in that if you have WHERE col LIKE 'A%', then the query plan will show that it can seek on col &gt;= 'A' AND col &lt; 'b', but most others don’t get picked up.

It’s not a ton of extra work, because it worked out the column value when it populated the index, and the parameter only needs to be shortened once. But I get that you might have a lot of queries to change. Sadly, it’s probably just what you have to do.