Total war (all money going to the war, millions of mobilized workers, etc.) would result in an economic collapse, which Russia is trying to avoid. Aside from "inconveniences" like Yandex AI not working after a data center hit, Russia's everyday life is largely unaffected by the war (at least compared to Ukraine's) - exactly because it is avoiding total war.
If Russia were desperate enough to finally go all in and have full mobilization (millions of conscripts, all industry working around the clock building nothing but drones and missiles, etc.), why would it start by attacking random EU countries instead of Ukraine itself? So I think it's very unlikely that anything is going to happen to Europe other than sabotage here and there. Remember that Putin is a KGB agent, and they're more about targeted tactical operations than strategic chess play.
The whole "special military operation" thing was itself just a way to quickly coerce Zelensky into signing an agreement by threatening force, without total war, but it fell apart, so they had to go this war-of-attrition route