You'll notice
Useful3 Signal2
Terminal notifications go through one path, and an unrecognised notification setting is reported as invalid.
What's wrong with this entry?
Anonymous. No account, no email.
What
The separate branches for iterm2, kitty, ghostty and terminal-bell notifications were replaced by a single call. The tengu_notification_method_used event now records which notification type was used, and records the configured channel as "invalid" when the setting is not one of the known values.
Evidence
tengu_notification_method_used
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
Related
Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.