The New Normal: What are employees looking for in new jobs?

Well over 20 million people quit their jobs in the second half of 2021. Some are calling it the "big quit," others call it the "great resignation."
But why is this happening? What are employees looking for in new jobs?
How can employers and employees deal with stress and burnout due to resignations or the surge in COVID-19 cases due to Omicron?
What benefits are employers offering their employees?