These are propaganda coups for the Russians. They’re dragging anchors and getting away with it.
Can’t EU countries block Russian vessels navigating the Baltic sea?
To access the Baltic sea from the North sea any ship must cross the Danish straits. Same question.
It gives the impression they’re winning and makes the EU and NATO look weak.
For balance, the last time this happened, when people were calling for nukes on Moscow, Sweden investigated, decided it was not deliberate, and released the ship
https://swedenherald.com/article/seizure-of-vessel-no-sabotage