currently, when exprs contains Alias, PushProjectThroughChild couldn't find the corresponding real column which results in empty exprs in Project.
select a, t2.v1 as max_b from t1 cross join (select max(b) as v1 from t1) t2;
t2.v1 column couldn't find the corresponding column in t2, so we need unalias t2.v1 to find the real column in table