I don’t know where this rumor started, but: Katniss was never canonically deaf after the first book and never wore a hearing aid.
Peeta was disabled: he was an amputee and this was especially important in the events of Catching Fire.
Other characters, like Chaff and the Avoxes, were also disabled, and they were also not featured in any of the movies (surprise, surprise). These are also legitimate concerns.
But in your criticism, do not criticize something that doesn’t exist.
Katniss suffers what is implied to be a perforated or ruptured eardrum: after the explosion, she bleeds from her left ear, has tinnitus in her right ear that eventually goes away, and vertigo and disorientation from the lack of hearing.
This is not to say that the damage isn’t serious: throughout the book she constantly tests her hearing, to no avail.
At the end of the book, after she’s won, this happens:
This is a plot point later in Catching Fire.
Reconstructed. Not a hearing aid. It’s heavily implied that Katniss had a tympanoplasty, an actual surgery in real life that is commonly used to treat victims of explosions who have suffered hearing loss (like these people who were at the Boston Marathon Bombings). A hearing aid is never mentioned.
Given that Suzanne Collins made sure to make Peeta’s prosthesis prominent and realistically portrayed, I doubt she would have forgotten to mention a hearing aid, even a permanent and implanted hearing aid, if Katniss had one. Instead, she brings up multiple times that Katniss had reconstructive surgery.
Criticize the exclusion of Peeta’s disability as much as you want. Hell, an argument can be made that Katniss should have been kept deaf in one ear rather than having it “fixed” with the Capitol’s magitech. And the movies certainly should have made it clear that she was deaf in one ear for the entirety of her first Games, and only underwent surgery after she was declared a Victor.
But unless I’m missing something (and I very well could be), Katniss did not have a hearing aid in the books, and so while the movies are lacking in their treatment of disabled characters, the exclusion of Katniss’ hearing aid is not one of them, because she never had one in the first place.