The instance of the original dev has shut down because he seized developement, but the project ist still doing fine. There's multiple public instances, but those are often unable to handle all user requests and get rate limited by google every now and then. I'm currently using invidious.tube, it has a good "real" uptime in my opinion (the site is up the whole time but might have issues like described above). I'm considering just self hosting should things get worse.