Do it for the netty logger specifically

loader/src/main/resources/log4j2.xml

@@ -17,10 +17,6 @@
         <MarkerFilter marker="FORGEMOD" onMatch="${sys:forge.logging.marker.forgemod:-ACCEPT}" onMismatch="NEUTRAL"/>
         <MarkerFilter marker="LOADING" onMatch="${sys:forge.logging.marker.loading:-ACCEPT}" onMismatch="NEUTRAL"/>
         <MarkerFilter marker="CORE" onMatch="${sys:forge.logging.marker.core:-ACCEPT}" onMismatch="NEUTRAL"/>
-
-        <!-- Netty reflects into JDK internals, and it's causing useless DEBUG-level error stacktraces. We just ignore them -->
-        <RegexFilter regex="^direct buffer constructor: unavailable$" onMatch="DENY" onMismatch="NEUTRAL" />
-        <RegexFilter regex="^jdk\.internal\.misc\.Unsafe\.allocateUninitializedArray\(int\): unavailable$" onMatch="DENY" onMismatch="NEUTRAL" />
     </filters>
     <Appenders>
         <TerminalConsole name="Console">
@@ -63,6 +59,15 @@
         <Logger level="${sys:forge.logging.mojang.level:-info}" name="com.mojang"/>
         <Logger level="${sys:forge.logging.mojang.level:-info}" name="net.minecraft"/>
         <Logger level="${sys:forge.logging.classtransformer.level:-info}" name="cpw.mods.modlauncher.ClassTransformer"/>
+
+        <!-- Netty reflects into JDK internals, and it's causing useless DEBUG-level error stacktraces. We just ignore them -->
+        <Logger name="io.netty.util.internal.PlatformDependent0">
+            <filters>
+                <RegexFilter regex="^direct buffer constructor: unavailable$" onMatch="DENY" onMismatch="NEUTRAL" />
+                <RegexFilter regex="^jdk\.internal\.misc\.Unsafe\.allocateUninitializedArray\(int\): unavailable$" onMatch="DENY" onMismatch="NEUTRAL" />
+            </filters>
+        </Logger>
+
         <Root level="all">
             <AppenderRef ref="Console" level="${sys:forge.logging.console.level:-info}"/>
             <AppenderRef ref="ServerGuiConsole" level="${sys:forge.logging.console.level:-info}"/>