A high Hr during a taper period is to be expected. You are getting rested and your sympathetic nervous system is on high alert. As we have said several times: HR is an imperfect proxy for effort. Unfortunately it is the best one we mountain athletes have.
ARE YOU TIRED during and after these Z1-2 hikes?
High HR with Low Effort means you are very fit, rest and ready to perform very well.
Low HR with High Effort is s sign of fatigue and can be a normal part of the training process but you should not expect god performance.
Probably this high HR now is an indication that you need to recalibrate your zones. No doubt your AeT and AnT are higher then when you started this process.