diff --git a/action.yml b/action.yml
index 310ccec8..483c70fc 100644
--- a/action.yml
+++ b/action.yml
@@ -88,6 +88,7 @@ inputs:
     description: "Maximum depth of the branch history fetched. **NOTE**: This can be adjusted to resolve errors with insufficient history."
     required: false
     default: "5000"
+    deprecationMessage: "This input is deprecated and will be removed in a future release."
   since_last_remote_commit:
     description: "Use the last commit on the remote branch as the `base_sha`. Defaults to the last non merge commit on the target branch for pull request events and the previous remote commit of the current branch for push events."
     required: true
diff --git a/diff-sha.sh b/diff-sha.sh
index 8235fc0f..d2e1bbb1 100644
--- a/diff-sha.sh
+++ b/diff-sha.sh
@@ -237,31 +237,6 @@ else
       PREVIOUS_SHA=$GITHUB_EVENT_PULL_REQUEST_BASE_SHA && exit_status=$? || exit_status=$?
     fi
 
-    if [[ "$INPUT_SINCE_LAST_REMOTE_COMMIT" == "false" ]]; then
-      if [[ -f .git/shallow ]]; then
-        depth=$INPUT_FETCH_DEPTH
-        max_depth=$INPUT_MAX_FETCH_DEPTH
-
-        for ((i=depth; i<max_depth; i+=depth)); do
-          if git diff --name-only --ignore-submodules=all "$PREVIOUS_SHA$DIFF$CURRENT_SHA" 1>/dev/null 2>&1; then
-            break
-          fi
-
-          echo "Fetching $i commits..."
-
-          # shellcheck disable=SC2086
-          git fetch $EXTRA_ARGS -u --progress --depth="$i" origin +"$GITHUB_REF":refs/remotes/origin/"$CURRENT_BRANCH" 1>/dev/null 2>&1
-        done
-
-        if ((i >= max_depth)); then
-          echo "::error::Unable to locate a common ancestor between $TARGET_BRANCH and $CURRENT_BRANCH with: $PREVIOUS_SHA$DIFF$CURRENT_SHA"
-          exit 1
-        fi
-      else
-        echo "::debug::Not a shallow clone, skipping merge-base check."
-      fi
-    fi
-
     echo "::debug::Previous SHA: $PREVIOUS_SHA"
   else
     PREVIOUS_SHA=$INPUT_BASE_SHA && exit_status=$? || exit_status=$?