A follow-up.
Guf Now the Dangerous site warning has been taken down from the fh4u.org subdomain. If you still facing this issue, here is what you can do.
1.Follow the instruction here, and Let Google know by report Incorrect Forgery Alert.
2.Do a self-check if you website contains any malicious scripts or inappropriate content. If you are confident everything thing should be find, that your website is safe for your visitors. Then:
2.Register a Google search Console account and follow the instructions, verify your fh4u.org subdomain.
3.If your website is safe. Your Dangerous site warning will be taken down in a few minutes. Or you will be notified if you need to fix anything.
Please let us know anything we can help.