The thinking might be "well the Europeans are going soft on Russia because they need to buy Russian energy, so if we destroy Russian energy sources then the Russians lose that leverage they have on the Europeans".
Russians saying Ukraine shelled an oil rig again.
I don’t get why they was wasting resources on oil rigs.
Alternatively, they're hitting them on the behest of NATO to try and reduce the Russian income.
Its not tactically sound but there might be strategic benefits, if the war ends up going long and if they can do enough damage.