Little known to the larger audience, C4C does not behave the same to all customers.
When switching from on-premise to the cloud we all needed to learn that standard modifications and skipping upgrades are in the past. Every three months, SAP upgrades C4C to a new release, with hotfixes inbetween. And we all have to live with them. Or do we?
SAP left a backdoor open: Each tenant comes with a set of backend parameters (SAP calls them "restriction entries") that can be changed by SAP per tenant. If you're paying attention to the release briefings, SAP often mentions that certain features are "in beta" and that they can be requested via incident. That's where the parameters come in: If you create that incident, SAP will "flip the switch" in your tenant and your C4C experience is suddenly no longer the same than that of other customers.
But these backend parameters are not only limited to beta testing of certain features. I've had cases where SAP released the entire code-base of an upcoming release for a specific user because of some issue with the current release. Meaning, all other users on the same tenant would still see the old behavior, but the user with the parameter set would see the new behavior. I could only speculate what else they could do, though I doubt they would be able to keep your system on an older release, in case you are wondering.
While I haven't seen those parameter tables, I tend to think of them as entries in RZ10 (systemwide) or SU01 (user-specific).
For sake of completion I do have to mention that C4C of course comes with a business configuration that allows different experiences for different tenants and an authorization system that allows different behavior for different users. What's little known, and this is the point of all the above, is that SAP have their very own internal business configuration, which they can use to influence your tenant- or user-specific experience.
Keep that in mind in case you're observing different behavior for different users or different systems (one user/system may have the parameter set - the other not). SAP do not always ask :-).