Q2. what other FRUITS are your favorite ? (on this question I used an array_filter_exclude to exclude the answer of Q1, and just leave the other fruits & it works perfectly)
Q3. Which of this fruits you use to prepare a flavored drink ? (on this question, the subquestions have to be all answers selected on Q1 & Q2, but when I try to use array_filter separated by a semicolon, i.e. Q1;Q2, it just shows the answers when they are selected on both questions, situation that is not possible because on Q2 just appears the answer that are not selected on Q1.)
The array filter only applies if the options in all of the filter question are checked.
If using "group-by-group" mode and all of the questions are on the same page, you could insert a hidden checkbox question and use it as the filter for Q3.