I have a cannister filter so it has an intake in the bottom back corner and the return spray bar put a flow up over the surface and it continues to the other side and down the tank wall...
So, I do have a few plants that have tops floating up to surface and one of my guys uses that plant (the flow just doesn't dislodge it too badly, although I do when I am moving stuff around and poor guy has to start over.)
The 2nd guy puts his up behind where the spray bar (horizontal) comes up over the tank corner. So there isn't a lot of flow there, he bit off some leaves and stuff and stuck them up there and puts his bubbles.
My 3rd smaller guy is SOL. He tries to investigate the other nests and gets chased off and he tries to put his up on the top near front of tank and the water flow just completely melts his bubbles almost right away, but he keeps chugging along since there are no other good spots for nests (plants, or low flow areas).
So for you betta, not that I am an expert but maybe get a plant or two that grow big enough to surface that can let the bubbles stick to it?