By default, when a Pathfinder class ability refers to a character's "level", it is referring to their levels in that specific class. From the Livro de regras básico, the multiclassing section on page 31:
Note that there are a number of effects and prerequisites that rely on the character's level or Hit Dice. Such effects are always based on the total number of levels or Hit Dice a character possesses, not just those from one class. The exception to this is class abilities, most of which are based on the total number of class levels that a character possesses of that particular class.
O Oracle Mistério is one of those class abilities. Since the feature only mentions level, we can conclude it uses the general rule (above) and refers to levels in the Oracle class.
the mystery manifests in a number of ways as the oracle gains levels.
Em contraste, o Amaldiçoar feature explicitly says that it also scales with non-Oracle hit dice (i.e., other class levels and racial hit dice), divided by 2 and rounded down.
An oracle’s curse is based on her oracle level plus one for every two levels or Hit Dice other than oracle.
Example: Suppose a mímico, which has 7 racial hit dice, somehow had 5 Oracle levels and 1 Fighter level. For their Mysteries, their effective level only counts Oracle levels (5). But for their Curses, their effective level equals 5 + ((7+1)/2), for a total of 9.