The HRV spikes can be real, at least in my case they were. Whoop helped me find out I was occasionally suffering from irregular heart beat. I am on meds now after spending time in the hospital.
My annoyance with Whoops metric is they do an average rather than a range. The huge spikes make an average useless. I have told Whoop that whilst the spikes are important to show they are outliers and should not count to the average, throwing recovery out until a month has passed and the high spikes disappear. My last Spike is due to drop off today. The meds are helping 
This is my post on the subject.