Arachnofiend |
Clumsy states that you "take a status penalty equal to the condition value to Dexterity-based checks and DCs, including AC".
Frightened states that you "take a status penalty equal to this value to all your checks and DCs".
Clumsy seems to define armor class as a DC, which would logically mean that Frightened also reduces your AC. This seems a little nuts though, and is more than the Shaken condition did in PF1 (where it penalized most everything except AC).