I'm not aware of any good reading material on it, and that's probably intentional. The FERC mentions the rise in power grid attacks somewhat in their annual report of 2023[1]. The incidents are underreported officially, and don't include police/FBI raids intercepting conspiracies, nor do they include the wave of attacks on cell towers. I only know about it because I spent quarantine in a community that had a nationwide dragnet of scanners listening exclusively for this stuff.

[1] - https://www.ferc.gov/sites/default/files/2023-05/23_Summer-A...