Join to find only max transaction count based of group

I am trying to find the max of transactions count based on type for each user.

I am expecting the output to be:

SELECT 
    DISTINCT(t.user_name), t.discom, c.*
FROM transactions AS t
LEFT JOIN (
    SELECT MAX(id) AS id, user_id, COUNT(id) AS `count` FROM transactions
    GROUP BY user_name, discom
) AS c ON c.user_id = t.user_id
GROUP BY t.user_name
ORDER BY c.count DESC

Although, the query is running, but its taking too much time (in minutes) just to fetch the data of mere 3500 users.

The solution:

SELECT user_id, subquery_1.type, cnt
FROM (
  SELECT user_id, type, COUNT(*) cnt
  FROM transactions
  GROUP BY user_id, type
  ) subquery_1
JOIN ( 
  SELECT user_id, MAX(cnt) cnt
  FROM (
    SELECT user_id, type, COUNT(*) cnt
    FROM transactions
    GROUP BY user_id, type
    ) subquery_2
  GROUP BY user_id
  ) subquery_3 USING (user_id, cnt);

On your version 5.5.62-cll the next query should produce correct output in most cases:

SELECT user_id, type, MAX(cnt)
FROM (
  SELECT user_id, type, COUNT(*) cnt
  FROM transactions
  GROUP BY user_id, type
  ORDER BY user_id, cnt DESC
  ) subquery
GROUP BY user_id

Pay attention - this is a trick which DOES NOT GUARANTEE that the output is correct.

fiddle