The problem probably you have two repositories for nginx binaries (possibly CentOS and nginx repositories).
I had the exact same problem, and was needed to remove and downgrade the nginx version to a working version:
# yum remove nginx
# yum install nginx-1.20.1-1.el7.ngx
May be needed remove other nginx packages too.
A *serious* problem:
Be careful and make sure you have the configuration file backed up ('/etc/nginx/nginx.conf'), because it will erase that file.
You will need to restore this file from backup, to keep the new downgraded binary nginx working.
Regards,
Netino