It seems plain as day to me that many people are far more hateful online than in real life, mostly under the disguise of anonymity and/or the physical divide. You can say some truly nasty things online that in the physical world would make you wake up in a hospital. There's no real correction mechanism online.
I can't believe the research doesn't address the point that some others here are making as well: the most harmful content is promoted, to the point that you exclusively see harmful content, which is then normalized. Social media promotes the crazy and silences the reasonables.
Not a word on the massively increased speed of information. There is no time to refute any point because the damage is done in minutes and garbage spreads, and then the next one comes.
Not a word on the complete lack of trust in information itself. In media, science, even simple verifiable facts. It doesn't seem to matter any more, people just make up their own facts.
And then the solutions:
"Invest in remedying the offline frustrations that drives online hate"
Ah, ok then. The solution is to just improve the world.