It's WFH and higher than expected inflation. As an employee you're likely facing substantial cost increases in food and potentially shelter. People haven't been traveling all that much during COVID - but I'd bet that travel and other expenses are going to see higher inflation in the near future.

Companies have grown accustomed to a 2% "performance" raise. This year it's suspect that 2% keeps you treading water. Why wouldn't we expect employees to move?