NOTICE: Constructor Method for WP_Widget is Deprecated since Version 4.3.0

I am seeing this message on the home page of my website as well as on the login page (I use WordPress for my website) and the dashboard section. Website link: https://beinggarifuna.com

Notice: The called constructor method for WP_Widget is deprecated since version 4.3.0! Use __construct() instead. in /home/adminname/public_html/wp-includes/functions.php on line 3624.

I have looked at various www.ads-software.com forums and seen many theories as to prospective problems on the matter but it appears none of them apply in my case. For example, I don’t have a WP_Widget in the coding of the website.

Can anyone help me get to the bottom of this? It is very distressing to see this deprecation notice forcibly splashed across my home page.