1/ algorithms already take this into account (as long as there is PC, most of HO cannot be detected … and for the ones that can be detected, they add the power control’s current attenuation into the HO detection threshold)
2/ the thresholds shall be tune so that PC will not be active anymore when a HO could be detected.
For example : Low level HO will appear at -90dBm (let’s say). In this case, PC will attenuate the signal only if the RXLev is better than -80dBm.
If RxLev is Lower than -80dBm, then PC is disabled (it means the TS is sent with maximum power).