In my case it' been exactly the opposite (App My Toyota 2024 version).
My Mk2 order appeared on the App immediately after it was confirmed by Toyota, and after a few days it suddenly disappeared.
It's not back on the App since then, and I have still to rely on my dealer and on messages by Toyota to get updates about my order.
From my direct experience (bought 4 Toyotas recently) and from what I see around, both the old and new version of MyToyota App don't follow fixed rules, and are affected by a quite erratic behavior.