That is not stealing. It is detaining.
It places those ships under deeper scrutiny. Will get inspected more, to check are they up to requirement. Which increases costs of maintaining it, as they will not be able to get away with skiping required procedures. Which in turn, reduces their profit margin.
That is it. And it royally pisses ziggers, because they will get LESS PROFIT.
And it fly nice with us, as they will have less income to fund military. Including campaign in Ukraine, and preparations for invasion in Baltics/Poland.
Detain and force one ship, release month later. Message has been sent. More ships will do their maintenance procedures, which will cost millions and millions of rubles.
In result, Baltic sea becomes safer (ships in better condition), and Kremlin gets less money, and on top of that, we managed to piss them off.