Foil doesn’t breathe or allow air in/out and so when a meat is foiled, any additional smoke cannot penetrate, stopping the smoking process in its tracks.
The biggest consideration when using foil is that when hot meats are wrapped, the steam cannot escape and turns to condensation, which in turn wets the surface of the meat, ruining any crusty bark that has formed during the cook and turning it to mush.
Peach/Butchers paper solves most of these issues because it allows the steam to escape the parcel and doesn’t make the exterior of the meat soggy, all while keeping the contents protected from the full assault of the smoker.
And because it doesn’t retain or reflect heat like foil, you don’t have to compensate for any extra cooking time.
Wrap your meats either close to or at the end of the cook time, to protect the meat from drying out and losing moisture as it rests holds at a lower temperature during service.
You can also use peach paper if the cook has gone quicker than expected, to try and retard any further darkening of the bark/exterior crust.