If they wanted to destroy it, they could have done so with artillery at any time since the Russians were pushed back from Kharkiv.
So if they aren’t going to leverage destroying it, what do you think they can get from it?
Ukraine: [looks at the completely open valves pumping gas full rate to Europe] “Can we launch long range strikes into Russia”
Europe: “No, we don’t want to upset the orcs”
Ukraine: [turns the valve once] “are you sure?..”
Europe: [sweating intensifies]
Except those gas pipes already go through Ukraine so if they wanted to threaten cutting the gas supply they could just cut the lines deep in their own territory.
Fact is, Ukraine understands that destabilising Europe by causing a gas shortage, while hitting Russias wallet, would make it much harder for European politicians supporting Ukraine to stay in power. They’re smart. They can see that their European allies are helping as much as they can, while still remaining popular enough at home to be able to keep up the assistance long term.