Steps to detect the issue:
1. Go to the user profile.
2. Open any user profile section. i.e 'Notifications Preferences'.
3. Open the 'Developer Tools' of your browser and inspect the elements.
4. You will find the main section headings, as well as sub-headings, both are using <h1> tags.
5. It's a best practice to have only <h1> tag on a page. So It's good to have <h1> for Main Section heading but sub-headings must be enclosed in <h2> tags rather than <h1> tags.