Why would they be? Russia doesn't tend to fund leftist groups. If they're actually a leftist group, it's far more likely to be about Palestine and of their own accord, or because of direct government oppression against them.
Last time I knew of an attack like this in Berlin, it was a direct retaliation after the government attacked their house with military tanks.
How will 20 year prison sentences get the power back on ("sort this out") ? Do you think 20n man-years of prisoner labor can install a new cable in the blink of an eye? Will the prisoners be forced to build a time machine so someone can go back and thwart their plans? Or how else do you envision this happening?
You're the one who asserted it would "quickly sort this out".
If you want to switch to talking about how to prevent similar events from occurring, surely you can imagine types of actors that even the possibility of 20 year prison sentences would not dissuade.
Very few electric customers are served by more than one substation, that substation and the distribution wiring between the substation and the customer are going to be a SPOF, except for the few customers with access to multiple substations.
Some substations don't have redundant feeder power either, although that's more often the case where geography makes it difficult (islands/peninsulas)... But the mention of wiring on a bridge might be an indication that is a geographically difficult area of Berlin?
This sentence kind of implies that foreign actors committed the attack, but a leftist group took credit for it[1].
[1]: https://www.rbb24.de/panorama/beitrag/2026/01/berlin-suedwes...