What if:

We are all aware about the characters being "nerfed", particularly the Sang'gres possessing the gemstones. They could have used blessings, protection spells or the full power of their elements just like what they did in the 2016 Requel. But what if these gemstones weren't able to wield such power as before because there's a "power or magical imbalance" that led to the Gemstones being nerfed, which is why they stood no chance against Mitena. Idk, maybe something has happened to Emre. That could be a plausible head canon that I can think of.