The datasheet says that the P1dB referred to the input of the mixer is -85dBm, please use this value even if the User's Guide suggests that the input signal should be stepped from -150dBm to -65dBm.
The IC datasheet is always the final authority when it comes to the specifications for an IC. In this case, the spec is -85dBm
into the mixer input. So the input tone power level to LNA1 should not exceed about -105dBm.