In bot "block kit" block sections, links formatted as *<http://example.com|:emoji_code: ...>* don't show the emoji in the link, but instead just show the emoji code in the link. This is different to how it's shown in the official client.

To reproduce, send a bot message with the following json: {"blocks":[{"type":"section","fields":[{"type":"mrkdwn","text":"*<http://example.com|:herb: Example>*\nHello"}]}]}

I recommend trying it out and comparing to how it looks in the official block kit builder.