In this talk, I will discuss the structure of QCD scattering amplitudes in the high-energy regime, known as the Regge limit. I will focus in particular on the factorization properties of amplitudes at next-to-next-to-leading logarithmic (NNLL) accuracy. At this level, factorization is violated by contributions associated with multi-Reggeon exchanges. We compute these terms using the shockwave formalism and the Balitsky–JIMWLK evolution equation, and by expanding the exact two-loop five-point amplitude in the high-energy limit. From this analysis, we extract for the first time the two-loop central emission vertex in QCD, a key ingredient for extending BFKL resummation to NNLL accuracy.