The App Store update release notes are exactly how you reach them — every existing user sees the "What's New" text when they're prompted to update. That's your direct line to them.

We already drafted this, but here's a version that leads with the news for existing customers:

> **Major size reduction — existing users, this one's for you.**
>
> This update shrinks the app from 1.87 GB down to about 160 MB — a 92% reduction. If you downloaded the original version, you can now reclaim nearly 1.7 GB of storage on your device by updating. All artwork, audio, and Apple Pencil drawing features are completely unchanged.

Want to use this, tweak it, or write something different? Once you're happy with it, you'll paste it into App Store Connect after the upload completes.