Wrong markers showing when using exposed filter on View with "Use AJAX: Yes"

Logging this on behalf of Vincent Jones who first came across this issue and reported it to me in private communication.

When a View that drives a Leaflet map (with or without Leaflet MarkerCluster enabled also) has an exposed filter as well as "Use AJAX: Yes" set, changing the filter results in a refresh of the map and its markers. However when the filter is set to a value that reduces the number of markers, then some of old markers belonging to the previous filter selection reappear. For instance , when initially the set contained 5 markers, and the set after changing the filter contains 2 markers, then with AJAX on, the old marker locations 3, 4 and 5 will remain visible on the map, with markers 1 and 2 correctly replaced.