Beginner web developer here, looking for how to fix this strange bug.

I downloaded this Bootstrap tutoring website (https://bootstraplily.com/free-tutor-website-template-made-with-bootstrap/#google_vignette).

After filling out the href for the about us link:

<li class="nav-item"> <a class="nav-link" href="#aboutUs">About Us</a> </li>

and adding the corresponding id

<div id="aboutUs" class="container py-5">

, I noticed that the navbar moves up the page (see the position of the scroll bar in this screenshot) once I click on the elements in the navbar. How do I stop this / why is this happening?