Crumbling infrastructure of the gas lines. It’s cheaper to abandon gas and abandon the aged broken pipes under the streets. In some cities the leaking losses in the ground are around 26%.
Bingo... and the politicians dare not speak that truth because it was severely impact the municipal bond rating which would accelerate these cities current decline into Third World status.
These places were not built with a focus on ongoing maintenance or replacement. That was somebody else's problem at some future date. It's now all coming due.
In some cities, there are still wooden water lines from two centuries ago:
https://www.hiddenhydrology.org/the-water-in-the-wood/