Re-enable slowmode incorrectly resets per-user cooldown without new message sent

Observed behaviour

Previous message timestamp is retained and used to calculate the cooldown. This persists between restarts too

Reproduction steps

Enable slowmode on a channel (6 hours for this example)
Send a message in the channel using an alt account
Disable slowmode on the channel using the main account
Re-enable slowmode on the channel using the main account (same or different duration)
Notice that alt account is on cooldown again without sending a message

Build information

canary build 664 (d3ccc95), Electron 41.2.2, Windows 11 10.0.26200 (x64), desktop canary 0.0.167, locale en-GB canary build 664 (d3ccc95), Firefox 150.0, Windows NT 10.0 (x64), locale en-US

Platform

Windows

Details

Expected behaviour A user should only be placed on slowmode after sending a message within the newly active slowmode window