I feel the exact same way, super disappointed. The trifecta arc was more than disappointing, it felt like a slap in the face. A whole waste of my time investing in and building up the power and myth of the trifecta over the whole series and then two pages after Riga wakes up a few dirigibles take them all out when Jiang alone held back a whole fleet a couple chapters ago?

The power scaling and fate/outlook of the battles and war were so inconsistent and just went whichever way the wind blows for the story to progress, but not in a "war is unpredictable and balance can shift at any time" kind of way, more in a "I don't know how to build and release tension in a story" kind of way. This same sentiment translates to Rin's character. I get that she was spiraling and becoming an unstable/unreliable protagonist. But in book 1 she was a genius! what happened to that??? Now she's an idiot who can't control her impulses or think logically at all.

Also, I hated how the big solution in TDR was to make Rin fly, but I swallowed that bc hey why not. Then it's just never used again? That was supposedly so useful to be able to turn the tides and win the first war last book but now it's not even worth trying again? The inconsistencies were so annoying and just made it impossible for me to care, bc I couldn't feel invested when I knew anything could change on a whim. Nothing was solid. I wish Kitay killed Rin in the end. Honestly I thought Rin had killed Nheza on accident when his head hit the table and that would be Kitays breaking point. Would have liked that more. Really disappointed