More sanctions should have been imposed when they shot down a passenger plane and killed several hundred Dutch civilians.
The interesting question is how compromised British politics has been. Lots of very suspicious things (secret Boris Johnson meeting against the advice of security services; appointment of Lord Lebedev), but UK support for the Ukraine war has been unwavering.
I really hope this war ends, and ends up with Russia paying for repatriations, including this case.
(what is happening is turning the asset freeze into asset seizure, but this is complicated - rightly - by human rights law, because most of the assets are nominally private)
But outside of Ukraine, none of it crosses physical borders; the sabotage of undersea cabling is all done in international waters, the internet is some kind of free for all as well, etc.
What should have happened is that the international community stepped up and sent a clear message, like "Russia will be cut off from the internet if they do not stop their digital attacks". Boundaries mean nothing if there are no consequences to violating them.
Losing them however does drop capacity because now you need extra work to get planes to final.