Unable to remove deleted smart mailbox from favorites

I seem to have stumbled onto a bug in Apple Mail. I had an "Unread" smart mailbox that I had added to the favorites section. I deleted it from the "Smart Mailboxes" section and it's gone. However its disabled ghost is still in the Favorites section. Because it's disabled, I'm unable to right-click to remove it.

I thought I might be able to address this by recreating it with the same name and removing it from favorites before deleting it. However that just creates a separate favorite, so it doesn't help.

I was able to recreate the issue by following the steps again and verified that this produces the ghost favorite smart mailbox issue:

1. Create a smart mailbox.
2. Drag it to the Favorites section.
3. Delete the smart mailbox.

Result: The smart mailbox remains in the Favorites section.

So now I have two ghost smart mailboxes I'm trying to get rid of. :)

I searched ~/Library/Mail for a file that might contain these favorites. I did find and delete SyncedSmartMailboxes.plist and SmartMailboxesLocalProperties.plist but that didn't do anything. I restarted my Mac too.

macOS Monterey 12.3.1

Mail 16.0

Anyone has an idea how to fix this?