According to the Economist, >"Estonia and other Baltic states have only a limited grasp over what was going on under the Baltic because of quirks of hydrology, scarce surveillance platforms and lack of communication between countries."

Here's a 2020 report https://www.fpri.org/article/2020/07/maritime-security-issues-in-the-baltic-sea-region/

Even just asking ChatGPT3, >"Another geological factor that can affect the surveillance of undersea telecom cables is the presence of underwater mountains, valleys, and trenches. These can make it difficult to lay and maintain cables, as well as to locate and repair any damages. Furthermore, the Baltic Sea is known for having a harsh marine environment, with strong currents and severe weather conditions, which can cause wear and tear on the undersea telecom cables over time. Finally, the Baltic Sea is known for having a high level of seismic activity, which can cause damage to pipelines and undersea telecom cables, making them difficult to locate and monitor."

I'm not saying it's sabotage just pointing out that speaking in certainty is fucking stupid. Think of how many corporations refuse to publish anything about data leaks because it looks bad to future customers and investors yet puts people at risk of identity theft, there's plenty of reason to not jump to conclusions in an area that actual experts have proven to be unknown.