Hello @Nir You can search for all available channels in the homepage under the “Explore” tab.
This particular channel that you mention was created 2 years ago when HiFi was a separate subscription. However, you have HiFi by default with your premium subscription and more than 90% of out catalog is available on HiFi now.
I have contacted our music team regarding HiFi Room anyway to confirm if they can include it under the Explore tab.
Thanks :)
 

@Nir the music team came back to me and confirmed that the hifi room channel has been deactivated and a revamp of the hifi playlists are in the works.
In the meantime both the hifi playlists and the deezer hifi editor profile are still available on the platform.
I hope that info helps :)