There will always be a bias in the answers when researching sensitive issues. This bias can be increased when the questionnaire is applied through a personal interview (since the participant is interacting with another person).
A good strategy to deal with sensitive issues is to apply a self-administered questionnaire, that is, it is distributed to the participants and they are asked to fill in by themselves. Furthermore, they should not be asked for their names anywhere. When starting, it is necessary to highlight the fact that the questionnaire is anonymous.