Overriding the target channel in an outgoing webhook does not work unless the target channel is the user that owns the webhook

Description:

I have an outgoing webhook that is supposed to react on triggers in a public channel and post the answer in a direct message. From what I understand, this should be possible to do by setting the channel field in the response to the hook.
However, this doesn't work for all users. It works when channel contains the username of the user that owns the hook, but not for other users

Steps to reproduce:

1. Create an outgoing webhook that gets triggered on messages, listens on a public channel, and does not have a script. answers should be sent as a (bot) user different to the user that owns the webhook.
2. In the response to a trigger, set the channel to a user that exists, and is not the owner of the webhook

Expected behavior:

I'd expect the message to appear as a direct message to the user according to the channel field in the response to the webhook.

Actual behavior:

From what I see, nothing happens. There's no message, and nothing in the logs. It works, when the channel field is not set (the response appears in the channel the hook was triggered from), or if the channel contains the username of the webhook owner.

Server Setup Information:

• Version of Rocket.Chat Server: 6.2.1

Client Setup Information

The behavior is consistent across different clients and operating systems

No files, tests, or entry points are named. Start by reproducing the webhook response with a non-owner user in the channel field, then trace the outgoing webhook handling. Done means the response posts a direct message to the specified user and existing behavior remains intact when the field is omitted or targets the owner.