To me it's pretty clearly the same targeted advertising available anywhere with the extra claim of using "voice data". It doesn't say what the voice data is or where it comes from. They could say that when people do google searches using Siri/OkGoogle/the microphone option on Google - it's information they would use in an anonymized way to target ads, or rather Google does on your behalf, and it's technically a derivative of voice data.

I'm skeptical this is what people might think it is. To be clear, I think most readers would interpret this as "your phone is surreptiously listening to you via your microphone." If that were true, then there would be telltale signs of resource draw. Handling rich audio data has practical costs, whether battery, CPU, network, memory, and/or disk; that data has to be stored, transmitted, and processed somehow. I've never seen analysis that shows that's happening. Not to mention this capability is beyond what audio capture APIs in Android and iOS offer, as far as I know.

Huffman is right that, in the end, the whole situation reflects a product problem: the native Reddit apps, both on desktop and on mobile, are ugly and difficult to use. (In particular, I find the nested comments under each post bizarrely difficult to expand or collapse; the tap targets for your fingers are microscopic.) Reddit didn’t really navigate the transition to mobile devices so much as it endured it; it’s little wonder that millions of the service’s power users have sought refuge in third-party apps with more modern designs.

One of the most upsetting things about the API changes, from developers’ perspective, is that many of their users bought annual subscriptions, and Reddit’s new pricing takes effect at the end of this month. That leaves them little time to make things right with their customers.