Superman's been gone for an entire year which is probably why Power Girl is starting to reach in her investigation (out of desperation) but the main reasons she feels Wonder Woman is involved is because she stands the most to gain, Pee-Gee is also aware of the rumours of the princess's relationship with Supergirl which only adds to her suspicion. Lastly, her Wonder Woman was VERY different to the current one in that she didn't come across as so ambitious while the current one has a history of ambition, from overthrowing her mother to being one of the loudest proponents for control during her time.