As someone who has also been bit by this, and with the only possible resolution being that I sign up for google services and register my site with them in the google search dashboard...

Fuck Google.

This is absolutely libel. They put a big fucking red banner on top of my site, telling the world that it's unsafe, using all the authority they have as one of the largest tech companies in the world.

In my case - it was a jellyfin instance I'd stood up to host family videos of my kids for my parents.

It was not compromised, and showed only a login page. I reported it as a false flag repeatedly, for weeks, with Google doing jack fucking shit.

Only after signing up in their search console and registering the site did the warning disappear.

They are abusively forcing people into their products. Fuck Google.

In case it wasn't entirely clear - Google can get fucked. Fuck Google.

There’s nothing wrong with your dislike of Google. No matter how much you dislike them, though, the word “libel” has a meaning that should be respected. To opine that a site is unsafe is simply not libelous.