I don’t have this and I have iCloud backup off for most things and so the 5gb free plan is more than enough. Is it possible you’re interpreting the reminder to

I don’t have this and I have iCloud backup off for most things and so the 5gb free plan is more than enough. Is it possible you’re interpreting the reminder to use the free tier of iCloud to back up essential iPhone data as an ad? If you don’t back up photos video and email you can likely remain on the free plan indefinitely. I don’t consider this an ad.