src/de/steamwar/bungeecore/listeners/NonFabricFabricCheck.java

@@ -54,7 +54,7 @@ public class NonFabricFabricCheck extends BasicListener {
             return;
 
         ProxiedPlayer p = (ProxiedPlayer) sender;
-        if (e.getTag().equals("minecraft:register") && new String(e.getData()).contains("fabric")) {
+        if (e.getTag().equals("minecraft:register") && new String(e.getData()).contains("fabric-screen-handler-api-v1:open_screen")) {
             BungeeCord.getInstance().getScheduler().schedule(BungeeCore.get(), () -> {
                 if (!sender.isConnected()) return;
                 if (!vanilla.remove(p)) return;