Fix #3537

core/src/main/java/org/geysermc/geyser/entity/type/player/PlayerEntity.java

@@ -119,6 +119,8 @@ public class PlayerEntity extends LivingEntity {
             setBelowNameText(objective);
         }
 
+        // Update in case this entity has been despawned, then respawned
+        this.nametag = this.username;
         // The name can't be updated later (the entity metadata for it is ignored), so we need to check for this now
         updateDisplayName(session.getWorldCache().getScoreboard().getTeamFor(username));
 
@@ -339,6 +341,8 @@ public class PlayerEntity extends LivingEntity {
             this.nametag = this.username;
         }
 
+        System.out.println(this.username + " " + this.nametag + " " + needsUpdate);
+
         if (needsUpdate) {
             dirtyMetadata.put(EntityData.NAMETAG, this.nametag);
         }

core/src/main/java/org/geysermc/geyser/scoreboard/Scoreboard.java

@@ -352,7 +352,8 @@ public final class Scoreboard {
             // With the player's lack of a team in visibility checks
             updateEntityNames(remove, remove.getEntities(), true);
             for (String name : remove.getEntities()) {
-                playerToTeam.remove(name, remove);
+                // 1.19.3 Mojmap Scoreboard#removePlayerTeam(PlayerTeam)
+                playerToTeam.remove(name);
             }
 
             session.removeCommandEnum("Geyser_Teams", remove.getId());

core/src/main/java/org/geysermc/geyser/scoreboard/Team.java

@@ -65,7 +65,14 @@ public final class Team {
             if (entities.add(name)) {
                 added.add(name);
             }
-            scoreboard.getPlayerToTeam().put(name, this);
+            scoreboard.getPlayerToTeam().compute(name, (player, oldTeam) -> {
+                if (oldTeam != null) {
+                    // Remove old team from this map, and from the set of players of the old team.
+                    // Java 1.19.3 Mojmap: Scoreboard#addPlayerToTeam calls #removePlayerFromTeam
+                    oldTeam.entities.remove(player);
+                }
+                return this;
+            });
         }
 
         if (added.isEmpty()) {