Since late 2024 (starting with kernel 6.11+), CachyOS’s default linux-cachyos kernel is compiled with Clang + ThinLTO for better performance. This is intentional and recommended.
However, many out-of-tree modules (like it87, some DKMS drivers, or manual builds) assume a GCC-built kernel or don’t fully support Clang’s build environment, leading to mismatches.