Based on the Lottie specification differences I just found, it seems that the export uses the new track matte syntax, but Flutter parses it according to the old adjacent matte rules, resulting in the entire green layer being exposed immediately. I'm now making a minimal fix in this direction: change the matte association method in loading.json and update loading.lottie synchronously, without changing the vector path itself.
AI analyze:
lottie-flutter: 3.3.3