According to a recent post on Reddit from this afternoon, a glitch in the wildly popular augmented reality game Pokémon GO is causing some players to experience Pokémon that they've caught turning into different types of Pokémon that have the same amount of CP. If you're new to Pokémon GO or have just not played very much of it and are still learning details of the game, CP is the amount of "Combat Power" that every Pokémon in the game has. As your Pokémon level up they progress and get higher levels of CP which comes into play when battling your Pokémon against another who is defending a gym.
The Reddit thread states that there are a lot of reports for the glitch from various users, and if that's actually the case then this is certainly not an issue which is isolated to just a handful of players. Screenshots of the glitch show a Moewth being caught and then display that it transformed into a Ponyta after the fact. Short of being quite annoying for the players who are experiencing this problem, the glitch doesn't seem to be game breaking in any way but it can be frustrating to have gone in search of a particular type of Pokémon only to have it turn into something else right after it's been caught, and as noted by the poster, INFEKTEK, a player could potentially use up a decent number of items to catch that Pokémon in the process, which then results in them losing items they wouldn't normally use if it's a Pokémon of little value.
Although Niantic have not confirmed this themselves just yet, the reason for the glitch looks to have been caused by the update, which improved the game in a number of ways by adding things like avatar customization, but also removed some things like the "nearby Pokémon" tracking feature which allowed players to know how close they were to a Pokémon they were hunting down. At the moment there has been no explanation from Niantic on the matter or whether or not they're working to fix the problem. This glitch also isn't the first one to pop up since the update has been pushed out to players, as some have been complaining about the game resetting.