Youtube pulled his account, so here's some Cliff Notes:
The suspect posted angsty, straight-to-camera diatribes under multiple channels, including prophetoftruth88, in which he sometimes referred to himself as the “prophet of doom.”
Many of the suspect's online diatribes revealed a torrid relationship with women. He also rambled about New York City Mayor Eric Adams and the city’s homeless, and said that thinking about desk-workers dying on 9/11 brought him joy.
“We live in a world of fuck-faces and scumbags,” Frank James ranted on YouTube. “When you see me happy when I watch videos of 9/11, that’s why.”
In one video from April 5, titled “Sensible Violence,” he put together a montage of more than 20 minutes of news clips on recent shootings around the country.
https://www.newsweek.com/brooklyn-subway-attack-being-investigated-terrorism-official-says-1697298
Brooklyn Subway Attack Suspect Previously Known to FBI and Cleared: Source
...The subway attack that injured multiple people in the New York City borough of Brooklyn Tuesday morning was initially considered an act of terrorism, an NYPD official told Newsweek shortly after the bloody incident. But the federal law enforcement source said the attack could not be classified as terrorism until a motivation is established.
At a press briefing hours after the attack, NYPD Commissioner Keechant Sewell said the attack was "not being investigated as an act of terrorism at this time." Asked if she would rule that out, she said law enforcement was "not ruling out anything" as officials continued to pursue the suspect and determine his motives....