I think there is a bug with bbcodes in phpBB 3.2.4, since when I was with phpBB 3.1.x I didn't have these issues.
I reported the issue here: https://www.phpbb.com/customise/db/extension/advanced_bbcode_box/support/topic/199311?p=666166#p666166
– But I think it may be related to phpBB than that extension.
The issue is that now a lot of my board has unwanted bbcodes posts, because of this bug. – since after the upgrade, a lot of the posts with bbcodes were re-parsed on my board – I guess by the built-in CRON job?
Let me know if you have any questions or suggestions??