If I go to a particular Sci-Hub mirror and it's down, I often go to the Wiki page to see the different TLD options. Same for checking some of my favorite Torrent trackers. I don't use Google for any controversial searches anymore, but if Wiki continues to degrade in quality, I'll really be SOL.
The only thing that consistently works for me is the Telegram bot.
>If I go to a particular Sci-Hub mirror and it's down, I often go to the Wiki page to see the different TLD options
You can still Google Sci-Hub, and find plenty of pages listing active mirrors.
Notably, https://www.sci-hub.pub is the top hit for me, and is reliable enough.