URLs with underscores don't link correctly

[SethFalco]

Steps to reproduce

1. Be in any chat room.
2. In a message, send a URL that contains characters used in Markdown.

Example:
https://openuserjs.org/scripts/victornpb/Undiscord_-_Delete_all_messages_in_a_Discord_channel_or_DM_(Bulk_deletion)

Raw:

https://openuserjs.org/scripts/victornpb/Undiscord_-_Delete_all_messages_in_a_Discord_channel_or_DM_(Bulk_deletion)

What happened?

The underscores will render the Delete_all_messages_in_a_Discord_channel_or_DM in italics. Everything to the left of it will get linked, while everything to the right becomes plain text.

Currently, a workaround is to just wrap the URL in backticks.

What did you expect?

I would expect whatever processes Markdown to skip URLs.

Operating system

Ubuntu 20.04

Browser information

Firefox 91.0.1 (64-bit)

URL for webapp

develop.element.io

Homeserver

matrix.org

Have you submitted a rageshake?

No

[robintown]

Duplicate of #4674