Hello,
I've moved your topic to English forum, as could be useful for other users
Yes, due to security patches (i think) in Joomla 3.8.4, it's good to clear all caching after update. (maybe in your case, just a clear all caching and gzip as well, would have solved the issue...)
And it's always good to clear cache after a Joomla update (specially when using third party extension such as JCH Optimize).
Thank you for your feedback!
Best regards,
Cyril