Bernie is still critical of the DNC because the DNC is still trying to triangulate the Republicans and failing miserably. The DNC is owned by big money. They do their masters’ bidding.
Last year, Sanders gave the whole country a teachable moment on how to push back against the Oligarchs, the Corporations and the Banksters. Although he did not ultimately win the nomination his degree of success was far greater than anyone but Jeff Weaver expected. The DNC was not happy with this. It exposed their hypocrisy and moral turpitude.
There are many Democrats who would like the Party to come to Jesus and drop Neoliberalism like a bad habit. This hasn’t happened yet. The only question is, will it happen, and if so, will it happen soon enough?