Yi Peng 3 crossed both cables C-Lion 1 and BSC at times matching when they broke

October 2023 there was similar incident where Chinese cargo ship cut Balticonnector cable and EE-S1 cable. Chip named 'Newnew Polar Bear' under Chinese flag and Chinese company Hainan Xin Xin Yang Shipping Co, Ltd. (aka Torgmoll) with CEO named Yelena V. Maksimova, drags anchor in the seabed cutting cables. Chinese investigation claims storm was the reason, but there was no storm, just normal windy autumn weather. The ship just lowered one anchor and dragged it with engines running long time across the seabed until the anchor broke.

These things happen sometimes, ship anchors sometimes damage cables, but not this often and without serious problems in the ship. Russians are attempting plausible deniability.

What are some concrete reasons why someone would want to damage these cables? Who benefits?

Russia wants to end NATO without going to war with NATO.

NATO's political unity and ability to respond is tested with these attacks. Russia does them one after another gradually escalating. Russia maintains plausible deniability or does so small operations that they can always walk them back.

Eventually, some country invokes Article 4 or 5 consultations. Russia hopes that US, Hungary, or Germany waters down NATO response. The conflict continues, but between individual countries not under NATO. NATOs as a organization may continue, but raison d'être is gone.

This is strange to me because this is basically forcing drills that better prepare their enemy.

If you never go to war with your enemy, your enemy's continued preparations are wasted money and resources (both political and economic), aren't they?