The Pokémon that you hatch inside an egg is determined at the moment you receive the egg. Nothing after that can affect the Pokémon that is in there. CP, IVs, moves, everything is set. (See this post on Reddit for example to prove that even moveset is predetermined.)
As such, the trainer level that you were at when you hatched the egg is irrelevant. Only the trainer level you were at when you received the egg is relevant. So if you spin a 10km egg at level 2, and then wait until you're level 20 to hatch it, it's still max level 2.
Insomuch as maximum CP is determined, even that is irrelevant; IVs are the sole determiner of maximum eventual CP. This is discussed in this question/answer for example, particularly in the second answer.
Also note that the (very old) Attack bug (where attack was directly proportional to pokedex #) did not affect eggs, so that's not related to the possible difference.