Info on official forum: https://forums.malwarebytes.com/topic/256701-what-happened-to-hphosts-website/?tab=comments#comment-1370003

We are currently restructuring hpHosts and it will no longer be updated. You could however check out our browser extension product.
...
we're no longer able to support that service

Discussion: https://www.reddit.com/r/uBlockOrigin/comments/fsgy4b/hphosts_ad_and_tracking_servers_link_down/