Well, some updates to a survey won't have any negative effect on existing data. If you're doing updates that will affect existing data, Survey123 Connect will give you a warning before you publish. If you decide to proceed, it is recommended to download the data from the Feature Service as a FGDB before republishing.
Look at the "Update Surveys" section of this documentation for more info.
Best,
Katie
“The goal is not simply to ‘work hard, play hard.’ The goal is to make our work and our play indistinguishable.”
- Simon Sinek
