diff --git a/.changeset/neat-hats-breathe.md b/.changeset/neat-hats-breathe.md
new file mode 100644
index 00000000..96eb23b2
--- /dev/null
+++ b/.changeset/neat-hats-breathe.md
@@ -0,0 +1,5 @@
+---
+"changesets-gitlab": minor
+---
+
+feat: try `allDiffs` api first and fallback to `showChanges` when unavailable
diff --git a/src/comment.ts b/src/comment.ts
index 2be8fb49..06ebce40 100644
--- a/src/comment.ts
+++ b/src/comment.ts
@@ -4,13 +4,14 @@ import type {
   ReleasePlan,
   VersionType,
 } from '@changesets/types'
-import type { Gitlab } from '@gitbeaker/core'
-import type {
-  DiscussionNoteSchema,
-  DiscussionSchema,
-  MergeRequestChangesSchema,
-  MergeRequestNoteSchema,
-  NoteSchema,
+import type { CommitDiffSchema, Gitlab } from '@gitbeaker/core'
+import {
+  GitbeakerRequestError,
+  type DiscussionNoteSchema,
+  type DiscussionSchema,
+  type MergeRequestDiffSchema,
+  type MergeRequestNoteSchema,
+  type NoteSchema,
 } from '@gitbeaker/rest'
 import { humanId } from 'human-id'
 import { markdownTable } from 'markdown-table'
@@ -20,7 +21,7 @@ import * as context from './context.js'
 import { env } from './env.js'
 import { getChangedPackages } from './get-changed-packages.js'
 import type { LooseString } from './types.js'
-import { getUsername, TRUTHY_VALUES } from './utils.js'
+import { getUsername, HTTP_STATUS_NOT_FOUND, TRUTHY_VALUES } from './utils.js'
 
 const generatedByBotNote = 'Generated By Changesets GitLab Bot'
 
@@ -207,10 +208,10 @@ async function getNoteInfo(
 }
 
 const hasChangesetBeenAdded = async (
-  changedFilesPromise: Promise<MergeRequestChangesSchema>,
+  changedFilesPromise: Promise<CommitDiffSchema[] | MergeRequestDiffSchema[]>,
 ) => {
   const changedFiles = await changedFilesPromise
-  return changedFiles.changes.some(file => {
+  return changedFiles.some(file => {
     return (
       file.new_file &&
       /^\.changeset\/.+\.md$/.test(file.new_path) &&
@@ -219,35 +220,6 @@ const hasChangesetBeenAdded = async (
   })
 }
 
-/**
- * @see https://github.com/jdalrymple/gitbeaker/blob/52ef0e622de304d98afb811f4937560edefd8889/packages/rest/src/Requester.ts#L79-L86
- */
-export interface GitLabAPIError extends Error {
-  cause: {
-    description: string
-    request: Request
-    response: Response
-  }
-}
-
-const GITLAB_API_ERROR_CAUSE_KEYS = new Set([
-  'description',
-  'request',
-  'response',
-])
-
-// type-coverage:ignore-next-line -- https://github.com/plantain-00/type-coverage/issues/133
-const { toString } = Object.prototype // eslint-disable-line @typescript-eslint/unbound-method
-
-const isError = (value: unknown): value is Error =>
-  toString.call(value) === '[object Error]'
-
-const isGitLabAPIError = (error: unknown): error is GitLabAPIError =>
-  isError(error) &&
-  !!error.cause &&
-  typeof error.cause === 'object' &&
-  Object.keys(error.cause).every(key => GITLAB_API_ERROR_CAUSE_KEYS.has(key))
-
 // eslint-disable-next-line sonarjs/cognitive-complexity
 export const comment = async () => {
   const mrBranch = env.CI_MERGE_REQUEST_SOURCE_BRANCH_NAME
@@ -271,18 +243,32 @@ export const comment = async () => {
   let errFromFetchingChangedFiles = ''
   try {
     const latestCommitSha = env.CI_MERGE_REQUEST_SOURCE_BRANCH_SHA
-    const changedFilesPromise = api.MergeRequests.showChanges(
+
+    const changedFilesPromise = api.MergeRequests.allDiffs(
       context.projectId,
       mrIid,
-    )
+    ).catch(async (err: unknown) => {
+      if (
+        !(err instanceof GitbeakerRequestError) ||
+        err.cause?.response.status !== HTTP_STATUS_NOT_FOUND
+      ) {
+        throw err
+      }
+
+      const { changes } = await api.MergeRequests.showChanges(
+        context.projectId,
+        mrIid,
+      )
+      return changes
+    })
 
     const [noteInfo, hasChangeset, { changedPackages, releasePlan }] =
       await Promise.all([
         getNoteInfo(api, mrIid, commentType),
         hasChangesetBeenAdded(changedFilesPromise),
         getChangedPackages({
-          changedFiles: changedFilesPromise.then(x =>
-            x.changes.map(x => x.new_path),
+          changedFiles: changedFilesPromise.then(changedFiles =>
+            changedFiles.map(({ new_path }) => new_path),
           ),
           api,
         }).catch((err: unknown) => {
@@ -368,11 +354,9 @@ export const comment = async () => {
         )
       }
     }
-  } catch (err: unknown) {
-    if (isGitLabAPIError(err)) {
-      const {
-        cause: { description, request, response },
-      } = err
+  } catch (err) {
+    if (err instanceof GitbeakerRequestError && err.cause) {
+      const { description, request, response } = err.cause
       console.error(description)
       try {
         console.error('request:', await request.text())
diff --git a/src/utils.ts b/src/utils.ts
index 083930dc..cabea43b 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -177,3 +177,5 @@ export const FALSY_VALUES = new Set(['false', '0'])
 export const TRUTHY_VALUES = new Set(['true', '1'])
 
 export const GITLAB_MAX_TAGS = 4
+
+export const HTTP_STATUS_NOT_FOUND = 404