I’m not sure, sorry. I tested it on my phone and an emulator, and it works fine on both, so it has to be a device issue. I tried googling your questions, but found no solutions other than ‘play on an older model,’ which isn’t really helpful. Once the current chapter is finished (later this month) I’ll make an additional build using the most recent Renpy version, perhaps that will help.
Would you mind letting me know which model are you using? I’ll try to find someone with the same one to test it out on my end.