Because flutter_map_marker_cluster 1.1.1 depends on latlong2 ^0.8.1 and no versions of flutter_map_marker_cluster match >1.1.1 <2.0.0, flutter_map_marker_cluster ^1.1.1 requires latlong2 ^0.8.1. So, because this app depends on both latlong2 ^0.9.0 and flutter_map_marker_cluster ^1.1.1, version solving failed.
Because flutter_map_marker_cluster 1.1.1 depends on latlong2 ^0.8.1 and no versions of flutter_map_marker_cluster match >1.1.1 <2.0.0, flutter_map_marker_cluster ^1.1.1 requires latlong2 ^0.8.1. So, because this app depends on both latlong2 ^0.9.0 and flutter_map_marker_cluster ^1.1.1, version solving failed.
Fix: Update latlong2 from ^0.8.1 to ^0.9.0