I use LibreTube and it looks like half of the instances keep getting shut down and then get back up, and the speeds for all are atrociously slow that it is just better to watch it on YouTube on Firefox. I heard a while ago YouTube was blocking certain Piped instances but do not know if that is the same case right now.
If it helps, the NewPipe developers have been working on a full rewrite of the app, but I don’t know when it will come out.
That said, I would probably use invidious in browsers. I haven’t really had any problems with it whereas I’ve had nothing but issues with Piped for months.
Oh nice ! Do you know if there exists a mockup of the new UI ?