This mod slows you down when carrying heavy objects in general, which is realistic.
But in my opinion it would be even more realistic and immersive if in addition to that it would make you jump lower.
The "Supplementaries" mod, in 1.20.1, adds a potion effect (called "Overencumbered") that does exactly this (makes you slow and also low jump), and it is applied at the moment where you carry too many sacks in your inventory, and it increases the level of the effect depending on how many sacks you are carrying

It would be great if Carry On would give you this effect when carrying heavy items