Feed -> Subscriptions -> "+" icon at the top
Press the three dot menu -> Settings -> Instances -> Select a different instance.
Which instance you choose is up to you, a list of them and their locations can be found at https://github.com/TeamPiped/Piped/wiki/Instances.
There's also https://status.piped.video which allows you to view the uptimes of all public instances, and their might be added something like that to the instances api in the future too.
This has been fixed in https://github.com/libre-tube/LibreTube/pull/4736. (Not sure if you're the person that submitted the issue or someone else did.)
Requested here: https://programming.dev/post/320260. Please upvote it in order to become considered as a new community on programming.dev :)
Not yet, but it would indeed be a good idea :) I created a request for a community here: https://programming.dev/post/320260. Not exactly sure if that fits programming.dev, we'll see :)
YouTube is facing issues at the moment, so just get a coffee and wait for some time.