Link is to Trump's official Instagram. It's one of his favourite photos and is captioned "HOPE YOU ENJOYED INVESTIGATING ME / NOW IT'S MY TURN." It's widely being interpreted by QAnon and rightists generically as the beginning of at very least a round-up of Democratic Party leaders, most particularly from the Obama administration, who are, of course, responsible for everything bad, including COVID-19, and who are all guilty of treason. The attempt to investigate the Russian interference is a "soft coup." Dinesh D'Souza is one of the better-known neofascists calling for Obama's immediate arrest.
You're also seeing a revival of all the conspiracy theories during the Obama administration, including that he's secretly gay/Michelle is secretly a man, that he was never an American and not eligible for office, that everything about the Obama presidency will be undone full stop, and so on.
Really, it's the Flynn travesty at the Justice Department - which to them "proves" that Russian interference was a hoax and that it was being run by Obama personally - primed them for this. QAnon in particular is flipping out, saying "it's really happening!!!" as they have many times before.
Christ, this absolute idiocy is depressing. Moreso when you realise how much they mean it.