I think the first 2 at least were very unlikely to be sabotage. They were reconstructed, and the welding from that was not strong enough for the task.

Of course sabotage is a possibility, but Russia is driving everything beyond their limits. Even workers are demanded to work insane hours where shortage is worst.

Russia is destroying itself from the inside. If they get a little help from Ukrainian sabotage, it only means it will go a bit faster.
But Russian infrastructure is collapsing because it's poorly maintained and pushed beyond limits.

[–] ladicius 15 points 4 days ago* (last edited 4 days ago) (1 children)

Never attribute to malice that which is adequately explained by stupidity. Or by incompetence. Or by neglect. Or by corruption. Or by vodka.

[–] [email protected] 7 points 4 days ago (1 children)

All those things existed before. Perhaps something changed in their ship maintaining routine to cut costs.

[–] NOT_RICK 5 points 3 days ago* (last edited 3 days ago)

I’d like to highlight the Admiral Kuznetsov. Here’s my personal favorite from the wiki page

On 30 October 2018, the ship was damaged when Russia's biggest floating drydock, PD-50, sank, causing one of its 70-ton cranes to crash onto the ship's flight deck, leaving behind a 19-square-metre (200 sq ft) hole. One person was reported missing and four were injured as the drydock sank in Kola Bay. The ship was in the process of being removed from the dock when the incident occurred and was towed to a nearby yard after the incident.[11] The cost of repairing the damage was estimated to be RUB 70 million (about US$1 million).[75] The fallen crane was removed by the end of 2018.