Some sites take a blunt instrument approach and subscribe to a list of "bad actor" IP addresses. These lists often include VPN IP addresses because one person among 40,000 might have tried something suspicious. The VPN IP address gets listed, and tens of thousands of innocent people using that VPN get locked out.
I have no idea if that's the case here, but if you're using a VPN you could try turning it off and seeing if the issue goes away.
Another possibility is that your public IP address was changed by your service provider, and it now matches an IP address that was on a block list. 99% of people don't pay to have a static IP address. If the power goes out or you reboot your router, your ISP might assign a different IP address than you previously had.
It could be nothing related to IP addresses, but those are two possibilities I've run into in the past.
