Sorry to hear of the problem you are having.
I have tested it on my test site and i am not getting that error using latest version of Jevelin theme.
This can be displayed by plugin on your site so please try temporary deactivating all plugins except Unyson plugin and see whether everything works fine and then enable the plugins one by one to see which plugin is conflicting if any.
Also could you please share me the page URL from your site where it is displaying so that i can troubleshoot it?
I have this message for my plugin WP Super cache:
“Zlib compression Output activated!
PHP contains the data sent to visitors to your site. It is recommended to trigger this because with the expansion of compressed compression once, instead of compressing the same page again and again. See also # 21 in the Troubleshooting section. See this page for instructions on modifying your php.ini file.”
Would you mind if i log in to your site and do some troubleshooting? If this is ok then could you please share me your site log in details privately by adding them in the box having text “Click here to share private content. Only you and forum moderators will bee able see it.”?