Client-Side-Scanning is going to be implemented by the messaging app vendor. This means that it’s limited by OS or Browser sandboxing . Therefore it’s definitely limited to what the messaging app has access to. However, I’m not sure what the actual scope would be, meaning if all accessible images are going to be scanned or only the one being transmitted to someone.
The problem with being a long time renter, is that there is no guarantee that the real estate will always be available to you.
What if your landlord sells your house/appartment and the new owner wants to move in? What if the rent hikes eventually make it unaffordable for you.
Unless you own the property, you cannot plan with certainty for the long term.