feat: Disable client once flushed (#1904)

Author: kamilogorek

CHANGELOG.md

@@ -15,6 +15,7 @@ since we removed some methods from the public API and removed some classes from
 - **breaking** [core] ref: Use `SyncPromise` internally, this reduces memory pressure by a lot.
 - **breaking** [browser] ref: Removed `BrowserBackend` from default export.
 - **breaking** [node] ref: Removed `BrowserBackend` from default export.
+- **breaking** [core] feat: Disable client once flushed using `close` method
 - ref: Move internal `ExtendedError` to a types package
 - **breaking** [core] ref: Pass `Event` to `sendEvent` instead of already stringified data
 - [utils] feat: Introduce `isSyntheticEvent` util

packages/core/src/baseclient.ts

@@ -333,7 +333,9 @@ export abstract class BaseClient<B extends Backend, O extends Options> implement
    * @inheritDoc
    */
   public async close(timeout?: number): Promise<boolean> {
-    return this.flush(timeout);
+    return this.flush(timeout).finally(() => {
+      this.getOptions().enabled = false;
+    });
   }
 
   /**