The NEXT (Neutrino Experiment with a Xenon TPC) collaboration aims at the sensitive search of the neutrino-less double beta decay ($\beta\beta0\nu$) of 136Xe at the Laboratorio Subterraneo de Canfranc (LSC). The observation of such a lepton-number-violation process would prove the Majorana nature of neutrinos, providing also handles for an eventual measurement of the neutrino absolute mass. A first large-scale prototype of a high-pressure gas-Xenon electroluminescent TPC, NEXT-White, was operated at the LSC from 2016 to 2021. This 5-kg radiopure detector demonstrated the outstanding performance of the NEXT technology in terms of the energy resolution (<1% FWHM at 2.6 MeV) and the topology-based background rejection. NEXT-White also measured the relevant backgrounds for the $\beta\beta0\nu$ search using both 136Xe-depleted and 136Xe-enriched xenon. In this talk, the measurement of the half-life of the two neutrino mode of the double beta decay ($\beta\beta2\nu$) will be presented. For this measurement, two novel techniques in the field have been used: 1) a Richardson-Lucy deconvolution to reconstruct the single and double electron tracks, boosting the background rejection, and 2) a direct subtraction of the backgrounds, measured with 136Xe-depleted data. These techniques allow for background-model-dependent and background-model-independent results, demonstrating the robustness of the $\beta\beta2\nu$ half-life measurement and the unique capabilities of NEXT.