65534 is used by the kernel to represent a uid/gid which is outside of the container’s map.
This can only be observed inside unprivileged containers as they are the only ones with such a map in place.
It’s normal for the kernel filesystems (/sys, /proc, …) to show up as such as those paths are owned by real root and not by the container root. The same goes for anything that you pass from outside the container. Unless the owner outside the container matches a uid/gid in the map of the container, they will similarly show up as 65534.