To fix it, he would have to dismantle the entire structure. Hours of work.
If you haven't decided which one to download yet, these are the most highly-rated choices: Un-PreCompose (aescripts + batchframe) unprecompose plugin free best download
Using Unprecompose is straightforward:
Developed originally by (and now maintained by community giants like AEScripts), UnPrecompose does one simple, brilliant thing: It rips layers out of a precomposition and pushes them back into your main timeline while keeping all effects, keyframes, masks, and parenting intact. To fix it, he would have to dismantle the entire structure
While there are paid versions with advanced automation, there are highly-regarded free scripts and versions available: While there are paid versions with advanced automation,
If you're looking for the best "free" ways to get this functionality, here are the top community-vetted recommendations: Un-Precompose any and all layers (2024) - Adobe Community
Since After Effects doesn't have a native "Un-group" button for compositions, the community has built specialized scripts and plugins to handle it in one click. The Best Free Download: Un-Precompose by Batch Frame