Recurring event changes the time on day 11 onwards

i succeeded with the MySQL Statement:

UPDATE `[DB_PREFIX]_eb_events` SET `event_date` = DATE_ADD(`event_date`, INTERVAL 1 HOUR)

if you want to go in the other direction, use DATE_SUB() Function, This adds one hour to every event - in case you dont like it, you have to limit the query.

USE ON OWN RISK - BACKUP FIRST.