"Own" in this context means be responsible for. Peer review does not transfer ownership to peers but it does reduce risk of your code breaking. Other people should not understand your own code (and intent) more than you, so long as that is correct, while everyone in dev/ops shares responsibility of delivering service, you own and are responsible for the part of that service delivery that you authored simply because you are the person most qualified to resolve any issue that arise from that code breaking. If an SRE is keeping your code running then they own the code's uptime in as much as you have been able to communicate the parameters and configuration of the app, but at the end of the day, when there is a bug in the code you are the best person to fix it, so you own it.