Active category highlight not working correctly

[tusharaddweb]

The sidebar category navigation highlight is inconsistent:

Blocks category: Both "Blocks" and "Concepts" items highlight simultaneously (should highlight only "Blocks")
Concepts category: No items highlight (should highlight "Concepts")
Playground category: Only "Playground" highlights ✓ (correct behavior)

Steps to reproduce:

Go to ​https://developer.wordpress.org/news/category/blocks/
Observe both "Blocks" and "Concepts" are highlighted in sidebar
Go to /news/category/concepts/
Observe no items are highlighted

Expected: Only the selected category should highlight in sidebar