FU 8.5.13 doesn't exist yet

common/src/main/java/com/viaversion/viaversion/protocol/ProtocolPipelineImpl.java

@@ -53,7 +53,7 @@ public class ProtocolPipelineImpl extends AbstractSimpleProtocol implements Prot
     }
 
     @Override
-    protected void registerPackets() {
+    protected synchronized void registerPackets() {
         // This is a pipeline so we register basic pipes
         final Protocol<?, ?, ?, ?> baseProtocol = Via.getManager().getProtocolManager().getBaseProtocol();
         protocolList.add(baseProtocol);
@@ -177,7 +177,7 @@ public class ProtocolPipelineImpl extends AbstractSimpleProtocol implements Prot
     }
 
     @Override
-    public void cleanPipes() {
+    public synchronized void cleanPipes() {
         protocolList.clear();
         reversedProtocolList.clear();
         protocolSet.clear();

gradle/libs.versions.toml

@@ -4,7 +4,7 @@ metadata.format.version = "1.1"
 
 adventure = "4.14.0"
 gson = "2.10.1"
-fastutil = "8.5.13"
+fastutil = "8.5.12"
 flare = "2.0.1"
 vianbt = "3.2.0"