get_currentuserinfo is deprecated, unable to find location of the error

I was wondering if someone ever experienced this issue with Wordpress:

Notice: get_currentuserinfo is deprecated since version 4.5! Use wp_get_current_user() instead. In /public_html/wp-includes/functions.php on line 3658

I know I can simply replace it but I need to find the source first. (the file and line mentioned in the notice simply refer to the error message itself.)

So I deactivated all the plugins, it still showed up. The theme I’m using checked out too. I eventually found a plugin (Query Monitor) that should show the exact location of the error, but strangely enough it’s not listed in its overview.

Anyone know what’s left to do? Thanks so much in advance!

via Chebli Mohamed