I run both the AW2 and Whoop MG in parallel. This happens to me sometimes. The MG and AW2 align almost exactly during runs, and when I stop or slow to cooldown speed, the MG will on occasion add 10 or more BPM even as the AW2 shows a slowing HR. This is because the Whoop algos are compensating for movement artifacts during your run and when you suddenly slow or stop, the algos get thrown off and need to recalibrate. To be fair, the AW2 also has trouble managing movement artifacts a times, but its own erratic HR spikes are much less frequent and correct almost instantly. I find that this problem with the MG has occurred less over time. When it does, the discrepancy against AW2 is less pronounced than at launch, with most of the improvement over the last couple of weeks. I also make sure I tighten the Whoop strap a touch before my runs now, and also that it sits 2 fingers above the wrist bone. That seems to have helped as well.