Beep boop, I’m a bot! I dug through the forum to get you started. I sometimes get things wrong though, so do with this what you will until a human has a look.
This is the “Deceptive site ahead” warning from Google Safe Browsing. We can’t remove it for you, because only Google can lift a listing, and only after you request a review.
Our article on this warning says the listings come from automated scanners that judge what a site looks like, not what it’s for. New sites with little history are judged more strictly. One common false positive is a site whose first page is a login form with nothing to explain what it is or who runs it. A school management system is likely to look like that. The article suggests four steps:
Put a public homepage in front of the login. It should say what the site is and which school it belongs to.
Add an about page and contact details. If you collect student data, add a privacy policy too.
Use only your own branding, with no other company’s names, logos or login page designs.
Once that’s done, add the site to Google Search Console. Open Security Issues and request a review once, with a clear explanation of what the site is for.
The article covers all of this, including how to check what Google actually flagged:
I don’t know yet which of the causes applies to you. Does the address https://ksmartschool.great-site.net/ open straight to a login form, or to a page with content? And does Search Console’s Security Issues report list any example URLs?