Salah was below his best again in Liverpool's damaging 2-1 defeat at Chelsea on Saturday as he wasted several chances and failed to help out in defence.
He has been absent from the scoresheet in five of Liverpool's seven Premier League games this season and the champions have suffered as a result.
The loss at Stamford Bridge was Liverpool's third in eight days as Arsenal leapfrogged them to the top of the table.
Salah has scored just three goals and provided three assists in nine appearances in all competitions this season.
Even more alarming than Salah's statistics, mediocre by his stellar standards, was the sight of the 33-year-old taking little interest when Liverpool were under seige against Chelsea.
Without any protection from the forward, Liverpool right-back Conor Bradley was hauled off at half-time after earning a booking as he struggled to keep Chelsea at bay.
The killer ball for Estevao Willian's stoppage-time winner came from Salah's right flank, with Marc Cucurella advancing unchecked to set up the Brazilian's goal.
Cucurella revealed Chelsea manager Enzo Maresca told them to exploit the defensive space vacated by Salah.
"We know that Salah is always ready for the counter-attack, so we practised that and the manager said that the space might be there," he said.
Salah's lethargic display was in keeping with a major dip in form since the closing stages of last season.
He scored 29 goals in 38 league matches, earning the Premier League Golden Boot as Liverpool powered to a record-equalling 20th English title.
But after scoring twice in a 3-1 win against Southampton in March, Salah's influence has waned.
He netted just twice in his last 11 games in all competitions, with Liverpool crashing out of the Champions League against Paris Saint-Germain during his power outage.
After Liverpool clinched the title, Salah boasted he had convinced Reds boss Arne Slot to let him concentrate on scoring and creating at the expense of defending.
"I told him as long as you rest me defensively, I will provide offensively, I will show you the numbers. So I'm glad that I did," he said.
'You need to help'
But giving Salah so much freedom is starting to backfire as opponents expose the gaping holes left by that plan.
Former Manchester United and England star Wayne Rooney has joined the growing chorus of disapproval over Salah's work rate.
"We know he doesn't always get back and defend as much. But in the Chelsea game, his full-back is getting torn apart and he's watching," he said on the BBC's Wayne Rooney Show.
"When it's going well and you are scoring goals, the team will put up with that. But over the last week, I'd question his work ethic.
"Those leaders in that dressing room should be telling him, 'You need to help out'. He's looked a little bit lost over the last week."
Former Liverpool midfielder Danny Murphy agrees with Rooney.
"It feels like Mohamed Salah's lack of defensive work has become a little problem for Liverpool, especially against the better teams," he said.
Slot must solve the issue if Liverpool are to emerge from their malaise.
Intriguingly, he left Salah on the bench for the first hour of the Champions League defeat at Galatasaray last week, while conceding that decision might have led to his lack of sharpness against Chelsea.
"That's interesting. Did he create so much because he didn't play during the week or did he miss the chances because he missed a bit of sharpness that he could have had if he would played against Galatasaray? We will never know," the Dutchman said.
For now, Slot is preaching patience as he looks to get Salah back on track.
"It's not like every chance he gets is always a goal," Slot said. "We feel sometimes it is, because of what he has done so many times. But yeah he is a human being."
