I know "shapeshifting monster is behind an evil conspiracy" is a well-worn trope and Paizo has no shortage of such things, but do you ever think about the potential of there being a Doppelganger out there who's impersonating someone writing monster manuals and sending out misinformation to get people killed?

It can indeed be played seriously, but my mind immediately steers to the comedy potential of an author penning some very unflattering words about shapeshifters and mimics, so insulting (or perhaps revealing) that a Doppelganger kills+replaces them and issues a "correction" to their work.

The nature and veracity of this correction/"correction" is up to the DM.

... Following this plot thread lead me to 'a doppelganger falls in love with an author's works so much that when tragedy strikes and the author dies, the 'ganger takes their place to continue their legacy,' which is significantly sadder. They're not evil, they just tend to be selfish; there's nothing saying you can't have a benevolent few willing to carry on the lives of people they knew and loved who were taken before their time. at least until they get bored.