When the pandemic first hit there was a resolve: "We will chip in and all do extra and help the company get through this." That works for awhile, like how crunch works on a short term basis, but only if it is short term. However, when months turn to years and people find themselves doing their job and the job of their colleagues who left for higher pay over a year ago and the company that they put so much into when the company was in need now seems content to not rehire or promote it causes frustration, burnout, and eventually even more more turnover.
So, yes, pay. But also what that pay represents. A company, especially a corporation in a capitalist society only speaks one language and that is the language of money. If the company underpays an employee based on their market value what that company is signaling is that they do not respect the employee.