That's terrible! :0 At least there are *some* good brands.
Only good brand I've heard for betta flakes are Omega One. The protein is really high and ingredients are great, too. Just search up the most high quality pellets,(NLS, Omega, Attison's, Golden Pearl, etc.) And see if they have any betta flakes.
My female LOVES Nutrafin Max color enhancing flakes. They are a bit expensive, but they do have a lot of fish proteins and very little filler. Of course she only gets them as a treat (and she goes crazy for them), but I think they would be good for your male as a stable diet.
I feed the Omega One Betta Buffet flakes too. They're 43 percent protein (even higher protein content than the pellets) and my bettas love them. My little halfmoon doubletail can't eat pellets either even though all the others have no problem eating them (they're also Omega One and are *tiny*). I don't know if he's just too little or if his mouth is weirdly shaped. I can't see any noticeable difference physically.
His mouth looks fine to me. Male bettas tend to have lips shaped like that to help with blowing bubble nests. Maybe the pellets are just too big? Most pellets marketed for bettas are too big for their mouths. I feed Omage One tropical flakes: the first 6 ingredients are real fish, and it contains very little filler.