One in five key public sector workers is "actively considering" quitting and changing profession according to a new study, with employees reporting "serious disillusionment" with their work.
The TUC said its research revealed complaints about low pay, excessive workloads and feeling undervalued.
The TUC pointed out that public sector staff have been told their pay is being frozen, while the government has given NHS workers a 3% rise, which has sparked warnings of industrial action.
The group said Prime Minister Boris Johnson’s promise of a high wage economy is "farcical" while public sector pay is held down.
More than one in four of 1,364 public sector workers questioned said government policy on pay has made them more likely to look for another job.
The report warned that a "toxic mix" of low pay, excessive workloads and a lack of recognition is pushing key workers in the public sector to the brink, with many at breaking point and on the verge of leaving their profession for good.
The TUC published research on how much public sector pay has fallen in real terms since 2010, including:
£3,194 for paramedics
£2,469 for nurses
£1,490 for care workers
£1,519 for refuse collectors
£2,579 for firefighters
£2,003 for teachers
General secretary Frances O’Grady said: "These are the nurses, care workers and teachers that helped keep the country going through the pandemic.
"After years of our key workers being underpaid and our public services underfunded, this pandemic has to be a turning point.
"Ministers must use the Autumn Spending Review to end the public sector pay freeze and give all public sector workers a pay rise, and they must properly fund our public services too".
Unison assistant general secretary Jon Richards said: "It’s not surprising many key workers want out of public service.
"The government thinks below-inflation pay rises or worse are an acceptable way of showing gratitude. Up against this, many public servants aren’t planning to stick around.
"Higher wages for less stressful work are proving tempting. Demoralised health, care, council, school and police staff have had enough – and who could blame them?"
A government spokesperson said: "We recognise the incredible work that public sector workers have continued to do throughout the pandemic, and the challenges many of them have faced as key workers.
"That’s why we’ve continued to provide pay rises for over one million NHS staff, and a minimum £250 increase to public sector workers earning less that £24,000.
"We are committed to building a high wage, high skill economy and the latest figures show that those in the public sector benefit from a 7% pay premium compared with workers in the private sector".