Here "strong" refers to the people who are strong in their faith. They believe that God allows them to eat any kind of food. AT: "we who are strong in faith" (See: [[rc://en/ta/man/translate/figs-explicit]])
Here "the weak" refers to the people who are weak in their faith. They believe that God does not allow them to eat some kinds of food. AT: "those who are weak in faith" (See: [[rc://en/ta/man/translate/figs-explicit]])