Attackers on the site you’re trying to visit might trick you into installing software or revealing things like your password, phone, or credit card number. Chrome strongly recommends going back to safety
Error appears in Chrome and Firefox but not Edge as of today.
However, a lot of browsers and security systems tend to mark websites with a login page as it’s home page as dangerous. You might want to change that, and report your site as a false positive.
That’s because your website URL was flagged by Google Safe Browsing, which is used in both Chrome and Firefox. Edge does not use Google Safe Browsing, but Microsoft Smart Screen (which serves the same purpose, but doesn’t flag exactly the same URLs).