Employees who get ‘pinged’ by the app have to isolate at home for up to 10 days after coming into contact with a Covid positive case even if they test negative themselves.
A Wetherspoons in Weston-super-Mare had 75 staff forced to stay home this week, prompting calls for the system to be changed so that anyone who receives a negative result can go back to work.
Dave Critchley, executive chef and director at Lu Ban restaurant and bar in Liverpool, said: “We lost five people over the weekend at minimal notice after they were pinged by the app.
“When you are only a small business anyway losing five members of staff meant we had lost a quarter of our workforce.
“It was already a monumental task to take on this year to make up all the money we lost from last year because we've still got last year's rent and bills to pay.”
It comes as the latest data showed fewer people with Covid are falling badly ill, with just one in 100 NHS beds being taken up by Covid patients in England last week.
This is despite the fact that daily infections have risen above 20,000 due to the increase transmissibility of the Delta variant of coronavirus.
Industry body UKHospitality has called on the government to relax rules so staff can return to work after providing a negative test - something Mr Critchley said he supported.
“We are seeing 45,000 people in stadiums with no mask and no social distancing and all they've had to do is take a test in the morning, so why can't my staff do that,” he said.
“We are testing our staff every day with a lateral flow test and temperature checks. So why can't our staff still go into work if they've had a negative test?”
Meanwhile, it has been repoted that the Cabot Court Hotel, a Wetherspoon pub in Weston-super-Mare, saw 75 staff forced to self-isolate for 10 days after four colleagues returned positive tests.