This one says to look in the inspector but there is nothing super obvious. The trick is that the flag is encoded so you can’t do an easy search for it.

I couldn’t find anything at first, but there was a weird string I noticed in the about.html page

  <section class="about" notify_true="cGljb0NURnt3ZWJfc3VjYzNzc2Z1bGx5X2QzYzBkZWRfMWY4MzI2MTV9">
   <h1>
    Try inspecting the page!! You might find it there
   </h1>
   <!-- .about-container -->
  </section>

you can use cyberchef.com to put in this string and there is a magic option that will find which decoding method make some sort of sense which is pretty neat

What did I learn

Use cyberchef for easy decoding