Turn back on Time Machine reminders

I used to be reminded every 10 days to do a Time Machine backup ("No Backups for x days..."), and the Time Machine icon would have a "!" in it if I didn't. I haven't had these reminders for a while, and I'm not sure how I can turn them back on. I'm on Sequoia, and in Time Machine settings it says Backup Frequency: Automatically Every Hour. Any advice on this?