Yes, that is normal. It's called a bubblest.Mine make one almost every morning.
Very normal, it is a bubble nest. Usually makes do this when they like where they live, good enough for babies.
You should be happy if your betta is doing that. My male betta made a nest a year ago and since then he hasn't made another nest... But good for you
Just as everyone said, this is simply a bubble nest. Some think that this is a sign of health and happiness, and others say that it is only a breeding behavior. No matter which one it is, you can rest assured that it is definitely not a reason to be concerned.