The Ukrainians are flying drones filled with explosives into Russian refineries and we still don't think it was just the Ukrainians taking out the Russian gas pipeline?

That's a good reason to think it wasn't Ukraine not that it was.

They're in open war with Russia, are openly attacking their resource infrastructure, and are frequently posting excellent high quality footage of it.

Taking out the gas pipeline and then not using the attack for propaganda doesn't fit either their situation or their actions.

The pipeline had the additional complication that it was supplying heating fuel to Europe. Bragging about it to the Germans would have probably been a bad idea.

That's the thing though, at the time it wasn't supplying gas. Gazprom said it was having 'technical difficulties' (that the German equipment manufacturer denied) and had reduced the flows over time to zero to put pressure on the Europeans through high winter gas prices and low supplies.

Your broader point is correct though, admitting to blowing it up would be bad press to any party.