What problem does this address?

The problem is crucial and affects all blocks! Currently, users editing key blocks like core/group can—a common occurrence—click "Apply Globally" in the advanced options, causing irreversible changes until user discover Global Block Styles.

What is your proposed solution?

• Opt-in by theme.json and be sure user can easy reverse this:
• Provide link to Revisions in Editor Styles so user can reverse change inside Block->Advanced->Styles (Like: "Apply this block’s typography, spacing, dimensions, and color styles to all Group blocks. Check [link to revisions] to reverse this change.")