@Damon Chung the best way to keep some information private is to create a document in the online cloud storage of your choice (Drive, Dropbox, OneDrive and so on) and then link to that document from the card, sharing it only with those who should be able to see the restricted information.
Hi @Damon Chung
Welcome to the Community!
Unfortunately, there isn't a way to impose card level limits or field limits.
If this is something that you want to have, you could consider suggesting this as a feature request by looking at this help page on submitting feature requests, or by emailing firstname.lastname@example.org.
Sorry I couldn't be more help :(
If you had to thrive a new habit during a lockdown, what would it be? Trello
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event