https://musicbrainz.org/area/c38d8161-bec9-4f25-9846-9fe262f864cf/places includes ended (closed) venues, but doesn't show them in any different way. Depending on what the main purpose of the map is, I'd suggest one of two options:

If we want the map to be something like "here's where to go in this city", don't display the historical places at all by default (but offer a way to toggle them on).

If we want the map to be "look at all the places we know about for this area", display all places, but add either "(historical)", "(closed)" or "(YYYY-YYYY)" when looking at an ended one.