Not true. I've been a paid user forever and on the Android app they have definitely obscured the model selector. It's readily visible to me on desktop / desktop browser. But on the Android app the only place I can find it is if I click on an existing response already sent by chatGPT and then it gives me the option to re-generate the message with a different model.
And while I'm griping about their Android app, it's also very annoying to me that they got rid of the ability to do multiple, subsequent speech-to-text recordings within a single drafted message. You have to one-shot anything you want to say, which would be fine if their STT didn't sometimes failed after you've talked for two minutes. Awful UX. Most annoying is that it wasn't like that originally. They changed it to this antagonistic one-shot approach a several months ago, but then quickly switched back. But then they did it again a month or so ago and have been sticking with it. I just use the Android app less now.
Sounds like there are a lot of frustrations here but as a fellow android user just wanted to point out that you can tap the word ChatGPT in your chat (top left) and it opens the model selector.
Although if they replace it all with gpt5 then my comment will be irrelevant by tomorrow
