Level 40 is the maximum you can get to in Pokemon Go but it looks like that might be about to change. According to a datamine, references to levels 41 through 50 have been found in the game's code.
Trainers have been wanting an increase to Pokemon Go's max level ever since they managed to reach the top level. Years after those requests started, those players may be about to get what they want.
Specifically, references to awards at levels 41 to 50 were found. They are as follows courtesy of the PokeMiners:
What about XP?
However, references to the XP requirements for each of these levels haven't been found in the code. This either implies these details haven't been added yet or there will be some other criteria to ascend through the levels. It is likely the former, though.
The XP requirements weren't updated in the Game Master, so if this is correct the level up requirements would be based on something other than XP (or they just haven't updated it fully yet).
— PokeMiners (@poke_miners) April 16, 2020
Consequences for the game
Make no mistake, this is huge Pokemon Go news. This will give the numerous trainers who have been stuck at Level 40 more to play for.
At this stage it isn't clear whether any XP earned about the Level 40 criteria will be retroactive. It seems unlikely it won't be, however.
It's important to note that these levels refer to trainer levels and not Pokemon. That doesn't mean the max Pokemon level won't increase to beyond 40, though.
If it does there could be monumental ramifications on how the meta would play out. Firstly, it would completely change each Pokemon's maximum CP and make Stardust a more valuable resource than ever. Given just how much this would change the game, we think this will only apply to trainer levels.
Subject to change
Remember, this information comes from a datamine and is absolutely not official. Niantic have not announced or even alluded to any of the above. Therefore, it is subject to change.