Some of the headline features in this release are: the removal of support for the Itanium architecture, the first part of the futex2 API, futex support in io_uring, the BPF exceptions mechanism, the bcachefs filesystem, the TCP authentication option, the kernel samepage merging smart scan mode, and networking support for the Landlock security module. See the LWN merge-window summaries (part 1, part 2) and the (in-progress) KernelNewbies 6.7 page for more information.
What happened to 7 and 8?
Those were skipped to upset you :D
7 ate 9
Same as Windows 9
Seven is spending a very long time in jail for cannibalism.