I tested with “Health Check & troubleshooting” plugin and disabled all plugins and active theme to Default. I then ran audit again and still the same error, which then means there is no issue with plugins or theme.
No, your test is faulty, making your proof invalid.
Using the Health Check & Troubleshooting plugin to disable all plugins and switch to the default theme ONLY affects your administrator login session. Guest viewers (including external tools like Ubersuggest) still see the normal site with the normal theme and all plugins active.
If you truly want Ubersuggest to check the site without the plugins, you have to completely disable all plugins and switch to the default theme — without using the Health Check & Troubleshooting plugin. This is the only way you can rule out the theme and plugins.
But that won’t be necessary if you’d just take my word:
-1- The first title tag is from your Yoko theme.
-2- The second title tag is from the Yoast SEO plugin. Your screenshot clearly shows this. (The Yoast SEO plugin had a “Force rewrite titles” feature to fix issues like this, but I just installed the plugin and couldn’t find the feature anywhere.)
You probably don’t want to mess with your SEO plugin. And as your theme hasn’t seen any update in years, you have to take care of this yourself. Open your theme’s header.php
file and remove or comment out this line of code:
<title><?php wp_title( '|', true, 'right' ); ?></title>
That should fix your problem.