Class attribute not applied from “Additional attributes” in Layout Settings

Problem/Motivation

Steps to Reproduce

Class attribute from ‘Additional attributes’ in Layout Settings is not applied

1. Go to Manage Display of any block type.
2. Select the One Column or Two Columns layout.
3. Save the form.
4. Go to Layout Settings.
5. In Additional attributes, add a class (for example: class|hello).
6. Save the form.
7. Place the block on a page.
8. Inspect the rendered block

Actual Result

The class is not added to the block output.

Proposed resolution

The class added in Additional attributes (e.g., class|hello) should appear in the rendered HTML.

Other attributes added through Additional attributes are working correctly, but the class attribute is not being applied.