There's now a new `matrix_nginx_proxy_ssl_protocols` playbook variable, which controls the SSL protocols used to serve Riot and Synapse. It's default value is `TLSv1.1 TLSv1.2`. This playbook previously used `TLSv1 TLSv1.1 TLSv1.2` to serve Riot and Synapse.
You may wish to reenable TLSv1 if you need to access Riot in older browsers.
Note: Currently the dockerized nginx doesn't support TLSv1.3. See https://github.com/nginxinc/docker-nginx/issues/190 for more details.