Not it is not. In fact many of the container escapes we see are because of bugs in the container runtimes themselves which can be quite different in their various implementations. CVE-2025-31133 was published 2? months ago and had nothing at all do with the kernel - just like many container escapes don't.
Containers are a kernel technology for isolating and restricting resources for a process and its descendants. Once set up correctly, any escape is a kernel 0day.
For anyone who wants to understand what a container is I would recommend bubblewrap: https://github.com/containers/bubblewrap This is also what flatpak happens to use.
It should not take long to realize that you can set it up in ways that are secure and ways which allow the process inside to reach out in undesired ways. As runtimes go, it's as simple as it gets.
I am not saying that you should never update the OS, but a lot of of those container escapes have severe restrictions and may not apply to your specific config.