it looks like you changed the stat name but didn't update it in the navbar code.

const [showNav, setShowNav] = useState(false);
...
            <MDBNavbarToggler
              aria-controls='navbarSupportedContent'
              aria-expanded='false'
              aria-label='Toggle navigation'
              onClick={() => setShowBasic(!showBasic)}
            >
              <MDBIcon icon='bars' fas />
            </MDBNavbarToggler>

            <MDBCollapse navbar show={showBasic}>
...

The basic example in our documentation is correct, so I assume you used a different example. please send an example from which you copied it, we will fix it.