Shinyapps.io: data accessible to our cloud

Hi,

I was just reading what is the difference between RStudio connect, shiny server pro and shinyapps.io. For shinyapps.io there is this question:
Are you okay with the data that the application is pulling from being accessible to our cloud?

Can someone explain to me what this really means? Can someone else, than me, access the data behind the app I upload to shinyapps.io?

If RStudio Community is not the right place to ask this question, who/where should I ask?

I have kind of sensitive data so I'm not sure if it's safe to use shinyapps.io because of this sentence I posted above.