The issue is in the browser.js,
It has this wrong code:

isMatching: () => browserjsUrl.href,

Where it should be:

            isMatching: () => href === browserjsUrl.href,

You just have to edit the browser.js script to have it like this:

        'DNA-99524': {
            description: 'Browser.js version reported on FAQ page',
            isMatching: () => href === browserjsUrl.href,
            applyOnDOMReady: true,
            apply: () => {
                const browserjs_info = version();
                const addVersion =
                  createTextNode(`Today ${browserjs_info}`);
                document.body.appendChild(addVersion);
            },
        },

@ardilom-2: yeah, it neither works for me

The issue is in the browser.js,
It has this wrong code:

isMatching: () => browserjsUrl.href,

Where it should be:

            isMatching: () => href === browserjsUrl.href,

You just have to edit the browser.js script to have it like this:

        'DNA-99524': {
            description: 'Browser.js version reported on FAQ page',
            isMatching: () => href === browserjsUrl.href,
            applyOnDOMReady: true,
            apply: () => {
                const browserjs_info = version();
                const addVersion =
                  createTextNode(`Today ${browserjs_info}`);
                document.body.appendChild(addVersion);
            },
        },