Bettas are really good jumpers. As long as i have them for about 5 years i had 2 bettas jumped out of the tank. And one of them like about 2.5 years old and he never did it before. Luckily he survived only because someone hear the splash of the water and he was on the floor. Other one was on my desk for about 15 and he didn't survived. 2 others jumped out while I was changing them. So I learned it hard way.
Even now I have 10 bettas and when I feed them one of them always jumps, another one flaring all the time when I feed him. Other seems don’t care and just look for the food or fallow my finger.
Now I always recommend to leave a certain amount of space between the top of the tank and the water level.
I also know people and saw post when bettas jumped and fell in to the sink drain. It so sad but I really know someone who had this accident :( So now I change my fish away from it. I do 100% water changes so I take my fish out of the tank. I also always have clean disposable plate next to the tank. Actually one time fish jumped out while I took him out of the tank and landed on that disposable plate. He was absolutely fine.
So even if you use a net make sure you cover it with other hand. I don’t use net I scoop them with a cup. One of my betta go to the bottom of the tank when I change him. He is pain to couch and I have to do it with my hand.
Sorry for long writing though.