What percentage of down votes are users responsible for?
SQL casing shouldn't matter (much)
Every SQL developer I know writes their queries a bit differently. Case/style shouldn't matter much or at all, if the SQL code works but it's a bit sloppy. Favor substance over style. For example, these 3 queries are identical, as far as the database engine cares:
/* These are all exactly the same in SQL: */
SELECT FOO, BAR FROM TEST;
Select Foo, Bar From Test;
select foo, bar from test;


That being said...
...there are a few things we could probably improve in your own query...
Some indentation would feel nice, especially in the subqueries/CTEs. Some indentation will make your code much easier to read:
WITH foo AS (
    ... 
),
bar AS (
    ... 
)
--etc


Lines breaks
Line breaks...also feel nice, especially for breaking down business logic, which DownVoteWeight is (for instance), where it can be broken down into meaningful functions/operations. This one might deserve a bit more documentation.
SELECT 
    DisplayName, 
    UpVotes, 
    DownVoteWeight = ROUND(
        DownVotes / (SELECT DownVoteCount from DownVoteCount) * 100, 4
    )