Citations not deleted when user is deleted

Description:

Messages of a deleted user are still present in citations after deleting the user. Along with their name / username.

Steps to reproduce:

1. As user A go to any channel and post a message, i.e. "This text should disappear with me".
2. As user B go to the same channel, post another message citing user A's message.
3. Delete user A from the RC instance.

Expected behavior:

1. All messages of user A should be deleted.
2. The citation should be replaced with a notice that the user was deleted.

Actual behavior:

1. All top-level messages of user A are deleted.
2. The citation is still present along with the deleted user's name / username.

Server Setup Information:

• Version of Rocket.Chat Server: 6.5.0
• Operating System: Ubuntu Linux 20.04 LTS
• Deployment Method: snap
• Number of Running Instances: 1
• DB Replicaset Oplog:
• NodeJS Version: v14.21.2
• MongoDB Version: 5.0.15 / wiredTiger (oplog Aktiviert)

Client Setup Information

• Desktop App or Browser Version:
• Operating System:

Additional context

Relevant logs:

Start by reproducing the issue with two users: post a message, cite it from another account, then delete the original user. Trace the deletion and citation behavior using the reproduction steps in the issue. Done means the original messages are removed and the citation shows a deleted-user notice without the former name or username.