Optimizer in 8.0 in some cases not materializing subquery

[Benjamin Peikes]

We have a query that went from taking 2 seconds in MySQL 5.7 to 50+ seconds in 8.0. It appears it has to do with how the optimizer is handling some subqueries.

Example of query:

SELECT e.id, e.status_id, COUNT(e.id) AS cnt
FROM Events e
WHERE e.ent_id IN (1)
AND
NOT EXISTS
(
SELECT eam.account
FROM EventAccountMapping eam
WHERE
eam.event_id = e.id AND
eam.account NOT IN
(
SELECT uapt.account
FROM UserAccountPermissions uapt
WHERE uapt.user_id = 1
) /* Subquery 2 */
)

In 5.7, it was treating Subquery 2 as a subquery, and in 5.8, it's be treated as a dependent subquery, even though it is not dependent on the other tables

If I break this into 2 queries where the select from UserAccountPermissions saves the results in a temp table, and then use that temp table, it goes from 50 seconds to 2. If I actually generate the results fo subquery 2, and inline the results ( 'aaa', 'bbbb', 'cccc', etc), the query goes down to less than one second.

In 5.8, I moved the subquery 2 to a CTE, and that doesn't resolve the issue either. Is there a way to force a CTE to get materialized?