Hi
I do not understand why the minimum V1 is so high for the Flex calculation.
By Flexing, you have matched your performance to the runway length available so effectively end up with a Balanced Field Length where the Min V1 (continue) & Max V1 (stop) are coincidental.
When using TOGA you have more performance, so even at the min V1 (continue) you will be able to accelerate within the runway length available to VR. With TOGA on the long runway you now have a range of V1s and usually the software chooses the middle one.