diff --git a/grails-doc/src/en/guide/upgrading/upgrading60x.adoc b/grails-doc/src/en/guide/upgrading/upgrading60x.adoc
index 9ae9157f6b6..922c066df20 100644
--- a/grails-doc/src/en/guide/upgrading/upgrading60x.adoc
+++ b/grails-doc/src/en/guide/upgrading/upgrading60x.adoc
@@ -860,3 +860,49 @@ The `+` marker is opt-in and fully backward compatible:
 - Existing URL mappings without the `+` marker continue to work as before (splitting at the first dot)
 - No changes are required to existing applications
 - The feature can be adopted incrementally on a per-mapping basis
+
+===== 12.28 GormService API Changes
+
+The `grails.plugin.scaffolding.GormService` class has been updated to fix a thread-safety issue and improve API clarity.
+
+====== Changes
+
+1. The `resource` field type changed from `GormAllOperations<T>` to `Class<T>`
+2. A new `gormStaticApi` field of type `GormAllOperations<T>` was added with thread-safe lazy initialization using `@Lazy`
+3. The constructor no longer instantiates the resource class - it now stores the Class reference directly
+
+====== Migration Impact
+
+If your code extends `GormService` or accesses its fields:
+
+**Accessing GORM operations**: Previously the `resource` field provided GORM operations. Now use the `gormStaticApi` field instead:
+
+[source,groovy]
+----
+// Before (7.1.x and earlier)
+class MyService extends GormService<MyDomain> {
+    void myMethod() {
+        def result = resource.list()  // resource was GormAllOperations<T>
+        // ...
+    }
+}
+
+// After (7.1.x with fix)
+class MyService extends GormService<MyDomain> {
+    void myMethod() {
+        def result = gormStaticApi.list()  // use gormStaticApi instead
+        // ...
+    }
+}
+----
+
+**Accessing the domain class**: If you need the Class reference, the `resource` field is now properly typed as `Class<T>`:
+
+[source,groovy]
+----
+// Before
+Class<MyDomain> clazz = resource.getClass()  // awkward, resource was an instance
+
+// After
+Class<MyDomain> clazz = resource  // resource is now the Class itself
+----
diff --git a/grails-scaffolding/src/main/groovy/grails/plugin/scaffolding/DomainServiceLocator.java b/grails-scaffolding/src/main/groovy/grails/plugin/scaffolding/DomainServiceLocator.java
index cef45755687..2205001c12b 100644
--- a/grails-scaffolding/src/main/groovy/grails/plugin/scaffolding/DomainServiceLocator.java
+++ b/grails-scaffolding/src/main/groovy/grails/plugin/scaffolding/DomainServiceLocator.java
@@ -33,7 +33,7 @@
 /**
  * Resolves the appropriate service bean for a given domain class by:
  *   - Scanning only beans of type GormService
- *   - Matching via: ((GormEntity<?>) service.getResource()).instanceOf(domainClass)
+ *   - Matching via: domainClass.isAssignableFrom(service.getResource())
  *
  * Keeps a single shared cache for the whole app.
  */
@@ -72,28 +72,25 @@ private static <T extends GormEntity<T>> GormService<T> findService(Class<T> dom
 
         for (String name : names) {
             GormService<?> gs = (GormService<?>) ctx.getBean(name);
-            Object resource = gs.getResource();
-            if (resource instanceof GormEntity) {
-                GormEntity<?> ge = (GormEntity<?>) resource;
-                if (ge.instanceOf(domainClass)) {
-                    matchingBeanNames.add(name);
-                    if (match != null) {
-                        throw new IllegalStateException(
-                            "Multiple GormService beans match domain " + domainClass.getName() +
-                            ": " + matchingBeanNames
-                        );
-                    }
-                    @SuppressWarnings("unchecked")
-                    GormService<T> svc = (GormService<T>) gs;
-                    match = svc;
+            Class<?> resourceClass = gs.getResource();
+            if (resourceClass != null && domainClass.isAssignableFrom(resourceClass)) {
+                matchingBeanNames.add(name);
+                if (match != null) {
+                    throw new IllegalStateException(
+                        "Multiple GormService beans match domain " + domainClass.getName() +
+                        ": " + matchingBeanNames
+                    );
                 }
+                @SuppressWarnings("unchecked")
+                GormService<T> svc = (GormService<T>) gs;
+                match = svc;
             }
         }
 
         if (match == null) {
             throw new IllegalStateException(
                 "No GormService bean found for domain " + domainClass.getName() +
-                " using resource.instanceOf(..). Scanned " + names.length + " GormService beans."
+                ". Scanned " + names.length + " GormService beans."
             );
         }
 
diff --git a/grails-scaffolding/src/main/groovy/grails/plugin/scaffolding/GormService.groovy b/grails-scaffolding/src/main/groovy/grails/plugin/scaffolding/GormService.groovy
index ebd2be58f76..7ed8dbec29a 100644
--- a/grails-scaffolding/src/main/groovy/grails/plugin/scaffolding/GormService.groovy
+++ b/grails-scaffolding/src/main/groovy/grails/plugin/scaffolding/GormService.groovy
@@ -26,6 +26,7 @@ import grails.gorm.api.GormAllOperations
 import grails.gorm.transactions.ReadOnly
 import grails.gorm.transactions.Transactional
 import grails.util.GrailsNameUtils
+import org.grails.datastore.gorm.GormEnhancer
 import org.grails.datastore.gorm.GormEntity
 import org.grails.datastore.gorm.GormEntityApi
 
@@ -34,28 +35,30 @@ import org.grails.datastore.gorm.GormEntityApi
 @CompileStatic
 class GormService<T extends GormEntity<T>> {
 
-    GormAllOperations<T> resource
+    @Lazy
+    GormAllOperations<T> gormStaticApi = GormEnhancer.findStaticApi(resource) as GormAllOperations<T>
+    Class<T> resource
     String resourceName
     String resourceClassName
     boolean readOnly
 
     GormService(Class<T> resource, boolean readOnly) {
-        this.resource = resource.getDeclaredConstructor().newInstance() as GormAllOperations<T>
+        this.resource = resource
         this.readOnly = readOnly
         resourceClassName = resource.simpleName
         resourceName = GrailsNameUtils.getPropertyName(resource)
     }
 
     T get(Serializable id) {
-        resource.get(id)
+        gormStaticApi.get(id)
     }
 
     List<T> list(Map args) {
-        resource.list(args)
+        gormStaticApi.list(args)
     }
 
     Long count(Map args) {
-        resource.count()
+        gormStaticApi.count()
     }
 
     @Transactional