add migration note

Author: mydea

docs/migration/v8-to-v9.md

@@ -141,9 +141,15 @@ Sentry.init({
 - The `flatten` export has been removed. There is no replacement.
 - The `urlEncode` method has been removed. There is no replacement.
 - The `getDomElement` method has been removed. There is no replacement.
-- The `Request` type has been removed. Use `RequestEventData` type instead.
 - The `memoBuilder` method has been removed. There is no replacement.
 
+#### Other/Internal Changes
+
+The following changes are unlikely to affect users of the SDK. They are listed here only for completion sake, and to alert users that may be relying on internal behavior.
+
+- `client._prepareEvent()` now requires a currentScope & isolationScope to be passed as last arugments
+- `client._processEvent()` is now private (was protected)
+
 ### `@sentry/browser`
 
 - The `captureUserFeedback` method has been removed. Use `captureFeedback` instead and update the `comments` field to `message`.
@@ -207,6 +213,7 @@ This led to some duplication, where we had to keep an interface in `@sentry/type
 Since v9, the types have been merged into `@sentry/core`, which removed some of this duplication. This means that certain things that used to be a separate interface, will not expect an actual instance of the class/concrete implementation. This should not affect most users, unless you relied on passing things with a similar shape to internal methods. The following types are affected:
 
 - `Scope` now always expects the `Scope` class
+- The `Request` type has been removed. Use `RequestEventData` type instead.
 
 # No Version Support Timeline
 

packages/core/src/baseclient.ts

@@ -764,7 +764,7 @@ export abstract class BaseClient<O extends ClientOptions> implements Client<O> {
    * @param currentScope A scope containing event metadata.
    * @returns A SyncPromise that resolves with the event or rejects in case event was/will not be send.
    */
-  protected _processEvent(
+  private _processEvent(
     event: Event,
     hint: EventHint,
     currentScope: Scope,