Where are the Reminders app reminders stored if syncing in iCloud?

Are Reminders still stored with the Reminders App on both the iPhone/iPad when syncing using iCloud, or are they ONLY stored in the cloud?

I started syncing Reminders between my iPhone and iPad today using iCloud.

My concern is not having a backup of my Reminders if an iCloud bug/failure deletes them from the cloud.

My understanding, when NOT syncing with iCloud, that Reminders are stored as part of the Reminders app (are included in backup in iTunes). I save archived iTunes backups weekly so can recover from an earlier backup if needed. I backup to my computer, not to iCloud

If Reminders are stored only in the cloud, I will turn off Reminders on each device for iCloud before I do my weekly backup and archive (presumably if only they were only in the cloud, they would revert to the device if turned off), then turn Reminders back on. I'd rather not do that step if not needed.

Thanks,

Robert