In a screenshot for a community question I think I saw a field list where some of the field names started with "formula" followed by a typical field name.
I do something similar for lookup fields by starting the field name with the initials for the table or app that the data point is originating from.
I'm starting to use more formula fields for various purposes & am trying to figure out a naming convention that is comprehensible for average users. We do not lock down reports in our app so the field name format needs to be clear enough that when a user is creating a report & has three fields that appear to capture the same info (lookup vs text entry vs formatted font display of text entry, etc.) that they can understand which one is the right field for what they are trying to show on that report.