Too many requests. Please slow down?

Description:

We have one person who, when attempting to direct message another specific user, gets the error message. It happens regardless of browser or desktop client. We had her sign out and back in, we've deleted cookies/cache, etc.

"Error, too many requests. Please slow down. You must wait 58 seconds before trying again." Oddly, in the upper left corner, it states "User not found". Please see the attached image:

Steps to reproduce:

Honestly, I'm not sure how to reproduce this. None of the rest of our user base gets this error, when attempting to direct message the same person.

Expected behavior:

No error. A direct message window should appear.

Actual behavior:

See the screenshot, above.

Server Setup Information:

• Version of Rocket.Chat Server: 3.0.12
• Operating System: Linux
• Deployment Method: tar
• Number of Running Instances: 2
• DB Replicaset Oplog: Enabled
• NodeJS Version: 12.16.1
• MongoDB Version: 3.6.18

Client Setup Information

• Desktop App or Browser Version: For the person getting this error, it happens in Firefox and Chrome, and also in the desktop version of Rocket Chat.
• Operating System: Windows 10

Additional context

We have tried clearing this person's cache, cookies, their desktop app profile settings, and their desktop app cache. Additionally, we have tried disabling the DDP Rate Limiter. None of these things have resolved the problem. One thing to note, the person that she is trying to direct message was, previously, a former employee. When he left the company, we deleted his RC account. When he returned, we created a new one. I don't know if that is related, or not.

Relevant logs:

I'm not seeing anything in the logs.

No source files, tests, or entry points are named, and the report has no reliable reproduction steps. Start by reproducing the direct-message attempt with the affected user while tracing the server-side user lookup and rate-limit behavior. Done means the affected user can open a direct-message window without the error.