no, now actual fix :)

Author: cowtowncoder

src/main/java/tools/jackson/databind/cfg/MapperBuilder.java

@@ -1035,6 +1035,8 @@ public B withAllCoercionConfigs(Consumer<CoercionConfigs> handler) {
      */
     public B removeAllModules() {
         _modules = null;
+        // [databind#5481]: invalidate cached state when modules are modified
+        _savedState = null;
         return _this();
     }
 
@@ -1066,6 +1068,8 @@ public B addModule(JacksonModule module)
             _modules.putIfAbsent(dep.getRegistrationId(), dep);
         }
         _modules.put(moduleId, module);
+        // [databind#5481]: invalidate cached state when modules are modified
+        _savedState = null;
         return _this();
     }