mobile webpage link not clickable

I just discovered that my “About Us” webpage (https://tutoringbyada.com.au/about/) can only be accessed and viewed on a computer browser. On the mobile/tablet version, I can’t click on the “About Us” tab that leads to the right page. It used to work. I couldn’t figure out why or whether there’s a setting for it. Your help will be greatly appreciated.
Thank you.
Ada

The page I need help with: [log in to see the link]