I just wanted to talk about this for a moment, since a lot of people seem to be surprised and I think it's important information for being informed consumers of technology products.
If you use a cloud-connected device such as a security camera, the video is going to be uploaded to the servers no matter whether you have a subscription or not. If it wasn't, you would not be able to view the video at all in the app, and you wouldn't get any alerts. The way these cloud cameras work is that the app connects to the cloud service, and the camera connects to the cloud service, and that's where the video feed comes from. It simply does not work without going through the cloud. The subscription is just about whether you get access to any stored video history or not (and maybe things like enhanced alerts and object detection). There are security camera products that do not work this way, and you can buy them, but if you buy a cloud camera like a Nest or Ring, this is how it works.
You should also assume that any video or photos that go through a cloud service may be retained either briefly or indefinitely, and either intentionally or accidentally. This is an unavoidable result of the way these complex distributed systems work; it's not nefarious. I know there are people here who will not believe me, and that's fine, but I can say with certainty that Google is not storing 100% of video and images for all users forever. But that does not mean that every frame is deleted immediately, either (as we have clearly seen in this case). Some stuff is stored for a short period for processing. Other stuff may linger in caches, backups, or other ancillary data stores. Certain things may intentionally be retained for a longer period for various reasons. Sometimes they may be stored in ways that are trivial to access, and sometimes (usually in the more ancillary examples), it takes some real digging to piece it back together.
Two things can be true: not everything that goes to the server is saved, and anything that goes to the server might be saved. I realize that this nuance might be confusing if you're not technical, so it's easier to either assume "canceling the subscription means Google never sees anything" or "Google is lying to us and storing everything forever," but it really is neither of those.
Bottom line, if you're uneasy about having your information in the cloud service, do not buy a cloud-connected device. Buy one that records locally only. These have their own drawbacks, but you should make an informed decision about which tradeoffs make the most sense to you and your own risk profile. I personally don't worry about the cloud storage, but that's just me. No shame in making a different decision for yourself and your family.