Searchable toggle is not working in web contents

Issue

If I create a web content and turn the 'Searchable' switch off, it's still shown in my search results

As an administrator, you can search for web contents in two different ways:
1. You can search for web contents in the Search portlet which is located on any page you create
2. You can search for web contents in the Site administration -> Web content section
As it is stated in the Creating Web Content section of the documentation for Liferay DXP 7.1:

Disabling search for your article removes it from end users’ search results. Administrators can still search for it from Site Administration → Web Content, and the article can still be added to pages.
So disabling the Searchable switch in an article prevents it from appearing in the search results or in the Asset Publisher's dynamic selection.
The article will be visible, however, to an Administrator in the list of web content articles displayed in Site Administration, the Web Content Display portlet or the Asset Publisher's manual selection.

If the 'Searchable' option is turned off and you still see your Web content in the search results described in point 1, try to reindex your content. If that doesn't resolve the issue, contact Liferay Customer Support on Help Center