Navbar Doc item is not highlighted when browsing category generated index

[slorber]

Have you read the Contributing Guidelines on issues?

• I have read the Contributing Guidelines on issues.

Prerequisites

• I'm using the latest version of Docusaurus.
• I have tried the npm run clear or yarn clear command.
• I have tried rm -rf node_modules yarn.lock package-lock.json and re-installing packages.
• I have tried creating a repro with https://new.docusaurus.io.
• I have read the console error message carefully (if applicable).

Description

See in production

https://docusaurus.io/docs/category/getting-started

The docs "tab" should be highlighted when browsing the docs sidebar, but it's not when browsing category generated index

Steps to reproduce

Browse category generated index in production

Expected behavior

Navbar item should be highlighted

Actual behavior

Navbar item is not highlighted

Your environment

• Public source code:
• Public site URL:
• Docusaurus version used:
• Environment name and version (e.g. Chrome 89, Node.js 16.4):
• Operating system and version (e.g. Ubuntu 20.04.2 LTS):

Reproducible demo

No response

Self-service

• I'd be willing to fix this bug myself.