If Reddit is saying "it's $2 for the 300 calls per day" that is claimed for the mobile app usage they're correct looking at what they charge for API calls based on the developer saying that the average user does 345 calls/day from the mobile app.
From the app develop perspective who also has a polling back end and an apple subscription cut and maintaining the same profit as before on top of it all, they're likely looking at closer to $20/month for that same user (noting that previously they were charing $4.99 and it was almost all profit for that user).