1260 Craft and Crust is expected to be granted permission to keep the unauthorised layout of its premises in Liverpool Road despite objections from people living above and behind it.
South Ribble's planning committee will discuss the application after a local councillor asked for it to be "called-in" due to concerns locally.
But planning officers are due to tell the committee that insulation measures have been introduced to limit the noise to "acceptable" levels.
A report to go before councillors says the layout of the restaurant, which opened in November 2019, is completely different to the approved plans for Craft and Crust.
The premises have a much larger bar and neighbours have complained it is more of a pub with TV screens and standing areas than a sit-down restaurant as agreed.
"Since the restaurant commenced operating a large number of complaints have been received from the occupants of the first floor apartments in terms of noise and disturbance," says the report.
"Following investigations one of the causes appeared to be due to the altered internal layout."
Objecting to the application to keep the layout as it is instead of how it was approved, one resident said: "The floor plan doesn't follow the noise strategy that was first approved.
"The strategy didn't cater for a large bar and cellar (on the opposite side of the premises to that approved) or the extraction system located below the roofline.
"Unacceptable levels of impact and airborne noise can be heard. This prevents us from enjoying our home and has affected our well-being from the very first day of trading."
Another said: "The original planning was for a restaurant. Craft and Crust is a bar/pub with TVs and caters for standing customers, therefore increasing footfall of incoming and outgoing customers.
"Craft and Crust has a larger bar area than the original planning application for a restaurant. There is daily ongoing noise of people talking, walking movement, noise from equipment and furniture movement.
"The noise that filters into our flat needs to be resolved. For the last two years we have not been able to enjoy our home due to noise, odour and disturbance.
"We were led to believe that the planning conditions and the noise mitigation assessment would alleviate our concerns. This turned out to be far from the truth.
"We have little faith in the South Ribble planning and assurance process. This venue is trading as a pub and this is against its intended use. It is not a typical restaurant.
"There seems to be a desire not to upset residents who live near the Lime Bar (also in Penwortham), but residents who reside above commercial premises are forgotten and ignored."
The council's environmental health department at first refused to support the application to keep the unauthorised layout because it reduced the seating available from the original plan and had a "much larger" bar.
But after a noise report was produced and the premises were monitored it said "the suggested insulation level is now considered acceptable." The department added it had carried out its own assessments and concluded there was "no statutory nuisance from the site."
Officers have recommended that Thursday's planning committee should agree to the retrospective application to keep the altered internal layout as it is.