Not sure if this is mentioned in any release notes anywhere, but the .ko files (loadable kernel modules) that would live in /lib/modules/«kernel version»/ are now .ko.xz files. Looks like this happened starting with the 6.6 kernel. I discovered this a few minutes ago, while trying to count how many .ko files came with my 6.7.9 Debian kernel, with find /lib/modules/$(uname -r) -name \*.ko | wc -l and was surprised to see that the answer was 0. A suitably adjusted command find /lib/modules/$(uname -r) -name \*.ko\* | wc -l returns 4165