Corporations always raise prices when they can. The question is why they are able to raise prices now to levels they couldn't before, and as always the answer is a mix of government-created moats and monetary inflation.
The study authors have a different answer about why than you do, though. What they are claiming is that in concentrated markets (like most markets are), shocks like the pandemic allow for firms to raise prices beyond their increased costs, and so increase profits. They have a very interesting graph of after tax profit margins showing that firms in the US are more profitable now than they have been for 70 years, in fact.
Then as inflation increased, companies used that as an excuse too. "We have to raise prices because of inflation! It's not our fault your wages aren't keeping up!" and people believed it even as companies were making money hand over fist and pulling in record profits.
But when Covid lockdowns forced temporary price increases, companies didn't see the backlash. And so they just continue to do it, knowing the average consumer has no choice in many cases.