It may be that you have some kind of malware on your PC. This is what I have been able to find out.
."Google’s Safe Browsing technology examines billions of URLs per day looking for unsafe websites. Every day, we discover thousands of new unsafe sites, many of which are legitimate websites that have been compromised. When we detect unsafe sites, we show warnings on Google Search and in web browsers. You can search to see whether a website is currently dangerous to visit." (On Google Tansparency Report page).
I run a Malware Byte check periodically. It might be worth a try. It's available for both Macs and Microsoft computers.