Those don't look like any kind of Vmca to me.
If you notice, for some cases the speed increases with increasing weight, for others it decreases. If it was Vmca scheduled with weight it would be decreasing as the weight increases. It's a very odd behaviour if it is Vmca. In fact, sometimes the minimum speed occurs at a mid weight. I'm confused.
You couldn't share the identity of the type concerned, perhaps? It might explain what's happening.
Looking at Ac25-7A, it's fairly clear that altitude and temperature are the only variables allowed for scheduling Vmca:
If, at the option of the applicant, the AFM value of VMCA is to vary with pressure altitude and temperature, the test day minimum control speed and the corresponding thrust should be used to calculate an equivalent yawing moment coefficient (CN). This CN value may then be used to calculate VMCA as a function of takeoff thrust, thus permitting VMCA to be scheduled as a function of pressure altitude and temperature for takeoff data expansion and presentation in the AFM