Sorry, looks like maybe I confused myself a bit, since been working with Experience Builder a lot lately also.
The new Map viewer and the Classic viewer save the popup info in different formats/locations. EB reads popup info for forms from the new viewer, but search attributes, edit widget order from Classic. So, in EB I have to open/config popups/save it BOTH viewers, which doesn't overwrite the other settings.
However, I just re-tested, and it appears that in Field maps, it is honoring the Title that I set up in popup configuration of the new viewer rather than the classic.
When configuring the popups, you can type text or choose attribute fields for the text. If you put multiple in the title field, it will concatenate by default:
eg. "Fox ID = " {foxid_field}
prints : Fox ID = 151.275 (assuming that is the ID for that fox)
and: "Fox ID = " {foxid_field} " and OBJECTID = " {OBJECTID}
prints: Fox ID = 151.275 and OBJECTID = 1 (or whatever the attributes are for that particular record).
R_