Donbass is a part of Russia now, the referendum has been held, it has been officially annexed, the status of the new republics enshrined in the constitution. It will not become independent again, and the people there do not want independence, they wanted to be part of Russia. The de facto independence phase was a compromise they had to settle for because Russia wouldn't accept them yet as long as they still held out hope that Ukraine would abide by the Minsk accords. That phase ended after the negotiations failed last year.