Markdown Header ID in Kirby 4 broken?

The CMS Questions
1

Hello,

I am migrating a 2.5.x site manually to Kirby 4.1.0.
I found out that Header ID marking in Markdown is not working, but it was before.
According to the Markdown Guide the syntax is correct.

Example:

### My Great Heading {#custom-id}

This is my code:

## 1) [Allgemeine Geschäftsbedingungen](#agb)
## 2) [Widerrufsbelehrung](#widerrufsbelehrung) 

<br />
***
<br />


## Allgemeine Geschäftsbedingungen mit Kundeninformationen {#agb}
<br />
### Inhaltsverzeichnis

Thank you for checking

2

Is Markdown Extra enabled in your config?

3

It is and was.
But found out that this does not work in the config file, as it worked with Kirby 2.5.x:

'markdown.extra' => true,

It need to be this for Kirby 4.1.0 (at least):

'markdown' => [
         'extra' => true
       ]