A classic follow the money situation. The EU likely has tools to prevent this type of thing. Or at least fine after the fact in a way that would make such action unprofitable.
But they are working. They now have to buy through third parties, increasing prices and delivery times. That’s the entire point of sanctions; we all know they’re gonna get the stuff eventually anyway
European businesses and third countries are actively circumventing sanctions, providing Russia with sanctioned goods
And the same thing is happening in reverse as well. Instead of getting cheap Russian gas and oil directly, the EU now has to buy gas and oil through third countries at multiples of the prices that they were buying them before.
That's called 'shooting yourselves in the foot' (if perhaps not 'shooting yourselves in the head') and will lead to a lot of EU de-industrialisation. Germany is already in recession.