I just see "tap the notification" and "didn't get the notification?" brings me to a page that says "do not disturb active" and "you can allow clearspace anyway in Settings -> Focus".

I went to Settings->Focus->Do Not Disturb and added the Clearspace app to "Allow Notifications", but still see nothing.

Edit: ah, it's because iOS's own Screentime was blocking the Clearspace app, which was blocking the notification.