Could you elaborate how?
considering the great amount of miserable, unworthy lives (factory farmed animals, heavily abused and tortured humans, etc) that exist and will likely exist even in some amount in even the "utopian" far future, it's reasonable for someone who doesn't think this all this can be counterweighed by any amount of pleasurable lives to consider permanent extinction as good.
and of course in the short term, suffering focused ethics may entail antinatalism as your children can't suffer, be abused, abuse animals, eat factory farmed meat if you just don't have children.