One thing I will say in Sale Moor Blue's defence is that while it's unlikely lockdowns contributed to the violence in Southport and other places, in terms of people still suffering the cabin fever effects of being locked up, lockdowns definitely contributed to more and more normal people getting caught up in internet conspiracies.
Otherwise regular folk who didn't use social media were suddenly scrolling and scrolling on websites they'd probably never used before. The big example that always saddens me is that Google searches for "QAnon" shot up by over 200% between July and August 2020. A relatively fringe right-wing movement was suddenly hugely popular.
Spread that out to other right-wing conspiracies, coupled with constant TV coverage of migrants in boats and what have you, and you can see where events like Southport come from. Add in the fact that foreign websites are making up fake news and sending it to places like Facebook, GB News, etc. and it's hardly surprising what's happened.
Just as an example, which I've repeated several times, the rumour that the name of the attacker was Ali-Al Shakati was started by a fake website in India. That was then spread on social media by popular right-wing accounts, to the point where people still believe that's the attacker's name, even after the police have confirmed it isn't.
This is what social media's now doing to people. It's forming a barrier between the public and their trusted news sources. The same is also happening on the left, for what it's worth, but the effects are way more severe on the right - especially with older people or people who only opened social media accounts in lockdown. Time to pull the plug.