The two issues, export and library ought to be separate issues, but who knows. There are many reasons the Library quality might not match the Develop quality. See: Lightroom color issue Develop vs Library modules: Retouching Forum: Digital Photography Review and Develop module & library module aren't matching - my understanding is that Library IQ is compromised slightly for speed, I've seen that on my app. I suspect the Library discrepancy is a "feature" more than a bug; I wouldn't focus on it for now. Exports are clearly another matter. Questions remain unanswered: with what app are you viewing your export, and I'm assuming you're viewing them at 1:1? And as you seem to be noticing a new problem, do images edited previously show this problem? Perhaps you can upload a raw and xmp to see if others can duplicate.
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