Bug Report

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We shouldn't scale the totalCount here, we only scale the expBackoffCnt here.

You can reproduce it through
create tablet t(id int, a int, b int, primary key(a, b) nonclustered);
select * from t where id in (..); // Here the number of in expression should be as much as possible.

And the modifyCount != 0.

You can run the above SQL and check the estimate row count of the dataSource operator which use the index.