Markdown list with formatting rendering duplicate text

[hctrdev]

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Describe the bug
When rendering a markdown list in a card description, duplicate text is shown if the list item includes formatted text.

I observed this issue with bold formatting, but it appears to affect all markdown formatting (e.g italics and links)

To Reproduce

1. Edit the description of a card and include the following markdown:

- [ ] **Step 1:** Do something
- [ ] **Step 2:** Do another thing

2. Render the preview of the card description.

Expected behavior
The rendered markdown should show the Checkbox, followed by "Step 1" in bold, followed by "Do something" without formatting.

Actual behavior
The rendered description shows "Step 1" twice, once in bold, and once in raw markdown.

Screenshots
In edit mode:

In preview mode:

Client details:

• OS: Linux Mint
• Browser Firefox
• Version: 84.0.2 (64-bit)
• Device: Desktop

Server details

Operating system: Linux 4.15.0-128-generic #131-Ubuntu SMP Wed Dec 9 06:57:35 UTC 2020 x86_64

Webserver: Apache/2.4.38 (Debian) (apache2handler)

Database: mysql 5.7.32

PHP version: 7.4.13

Nextcloud version: 20.0.4 - 20.0.4.0

Deck version: 1.2.3

[reox]

duplicate of #2138