@Hassan_Nadeem,
Place your <div class="flag" data-status="Change"></div> inside a Rich Text component (or one sourced from a user profile table), and make sure it exists on every screen where your tab label needs to appear.
Then, copy the rest of the code into the Custom CSS box.
Please refer to: 
CSS Hack: Dynamic CSS in Glide
Additionally, for your information — the **data-status** (attribute) approach allows for more complex conditional styling. However, if your condition only has two states (`Change` and `unChange`), you can simplify the setup by using a **permanent class name** and control visibility directly through the Rich Text component itself.
In that case, within the CSS code I shared earlier, simply replace every
#page-root:has([data-status="Change"]) with #page-root:has(.flag)