Hello,
let me explain the use case: we have a class which receives SQL queries which are defined by users as part of our application metadata, so we do not know which are the aliases defined in the query beforehand.
As part of a dynamic processing we are doing in our class, we used the Query.getReturnAliases() method to just retrieve the aliases. By using this method, we were able to get the aliases without executing the underlying query.
If we now replace that deprecated method and use a Tuple query instead, we are introducing a change in terms of performance in our processing, as previously we did not need to execute the query to retrieve the aliases.