Hello, I don't speak German but this extension is not providing any zoom functionalities, I've tested the extension right now and I can properly enable and disable the black overlay without issue. Technically its not really possible to break a website permanently just by installing an extension, so please try to hard refresh to make sure nothing is cached. On the other hand, this extension has been built years ago when web dev was a different landscape so there are probably more modern solutions to testing the accessibility of your site nowadays. Alternatively you can always just turn off your monitor/display and try to navigate your website without it just with your keyboard, and you don't need an extension to do that. The expected route of using it though if you really want to, is to press the blindify icon to enable the black overlay, and press it again to turn it off. Alternatively please provide your Firefox version so we can potentially test it out there. Love, not hate 🫶