How is it enforced? IP or DNS?
According to this site https://bandaancha.eu/articulos/gobierno-tiene-lista-web-ofi..., they use SNI (https://en.wikipedia.org/wiki/Server_Name_Indication)
Enabling ESNI in Firefox should be a countermeasure (encrypted SNI extension of the TLS so that hostname is no longer sent in plain text)
https://superuser.com/questions/1346634/modern-browser-with-...