No one of suggested links to channel_v3.json for package control setting didn't work for me.

But this worked:

https://raw.githubusercontent.com/liuchuo/channel_v3.json/refs/heads/master/channel_v3.json

So, your channels setting in Preferences > Package Settings > Package Control > Settings should look like this

"channels":
[
"https://packagecontrol.io/channel_v3.json",
"https://raw.githubusercontent.com/liuchuo/channel_v3.json/refs/heads/master/channel_v3.json",
],

Found it here: https://github.com/liuchuo/channel_v3.json