It’s because of the electoral college. Most states give all their electoral college votes to whomever wins the state rather than dividing the votes equitably. This means Pennsylvania – a swing state – will go either all-red or all-blue. The state has a lot of fracking, and a lot of people making money off it, so Democrats are trying to appease pro-fracking to get votes.
The people getting harmed by fracking are stuck without anyone on their ‘side’, but will presumably be more likely to vote blue because that side favors more regulation and pro-environment stuff. Note that all Harris said was she wouldn’t ban fracking. She didn’t say she wouldn’t make it difficult to do. My guess is any attempts to make it cleaner will get crushed by Congress and the Corrupted Supreme Court that has sided against Unions, workers, citizens, and the planet – all to favor of their sugar daddies. So even if the next President wants to do something about fracking, it would be a hard to actually do anything.