Can't connect via ssh to ec2 instance (Amazon Linux 2) after Openssh upgrade

Hi,

There was an OpenSSH Vul. reported by our scans for Amazon Linux 2 EC2 Instance. I upgraded the server to OpenSSH_9.0p1 but I can't login to it now. I am getting the error "Server refused our key" when trying to connect via putty and "Failed to connect to your instance" via EC2 Instance connect. Is there any way I can reclaim my ssh access? Everything else is working normally and I can access the web application deployed on the server.

Thanks