Fix use-new-effect-indicator option for 1.13+ clients (#3127)

common/src/main/java/com/viaversion/viaversion/protocols/protocol1_13to1_12_2/packets/EntityPackets.java

@@ -17,6 +17,7 @@
  */
 package com.viaversion.viaversion.protocols.protocol1_13to1_12_2.packets;
 
+import com.viaversion.viaversion.api.Via;
 import com.viaversion.viaversion.api.minecraft.entities.Entity1_13Types;
 import com.viaversion.viaversion.api.protocol.packet.PacketWrapper;
 import com.viaversion.viaversion.api.protocol.remapper.PacketHandler;
@@ -146,6 +147,25 @@ public class EntityPackets {
             }
         });
 
+        protocol.registerClientbound(ClientboundPackets1_12_1.ENTITY_EFFECT, new PacketRemapper() {
+            @Override
+            public void registerMap() {
+                map(Type.VAR_INT); // Entity id
+                map(Type.BYTE); // Effect id
+                map(Type.BYTE); // Amplifier
+                map(Type.VAR_INT); // Duration
+
+                handler(packetWrapper -> {
+                    byte flags = packetWrapper.read(Type.BYTE); // Input Flags
+
+                    if (Via.getConfig().isNewEffectIndicator())
+                        flags |= 0x04;
+
+                    packetWrapper.write(Type.BYTE, flags);
+                });
+            }
+        });
+
         metadataRewriter.registerRemoveEntities(ClientboundPackets1_12_1.DESTROY_ENTITIES);
         metadataRewriter.registerMetadataRewriter(ClientboundPackets1_12_1.ENTITY_METADATA, Types1_12.METADATA_LIST, Types1_13.METADATA_LIST);
     }