It’s refreshing to read of a fridge performing well on gas , majority of threads complain of the fridges not cooling efficiently hence people using fans to dissipate the hear , in essence that’s what fridge does shifts heat from one place to another.
As Pauljenny correctly states there are many factors that can affect efficiency and it can be quite subtle
When I was gas testing in the south of France ,sometimes the manometer would rise like mad a sign the regulator could be letting by, often it wasn’t it was the cold gas expanding in the pipe work because the sun had come out...we used to let it stabilise a couple of minutes drop the pressure from opening a hob then re check for gas tightness .