They actually managed to upstream support on kernel 5.1, but break it on kernel 5.2, and IIRC only kernel >5.5 has the fix, which ubuntu still doesn't have support for.

I expect Canonical or Lenovo or both to test all release candidates of all kernel versions after release and make sure that the hardware actually works, and if it doesn't, prevent the release of a broken Linux kernel version.

That would be the minimum level of QA acceptable for a "certified" laptop.