Seems like every department at canonical needs to learn this on their own.

After all, they reinvented everything from DE to init system at least once in past.

(They also have their own containers, LXD. I actually really like that one, please keep working on that canonical)

What are some other bad mistakes that's been made?

22.04 uses the 5.15 LTS kernel. https://www.kernel.org/category/releases.html

But I assume as Ubuntu follows an April release schedule, it doesn't always match with an appropriate LTS kernel.

Ubuntu was originally designed as a desktop OS and its release cycle was synched with the GNOME 2.x release cycle.

Agreed. Ubuntu does use a stable kernel by default for LTS, at least for ISO installs. This problem occurred within the HWE (hardware enablement) release train, where they backport non-LTS kernels and features, which for some reason they use as a default in various places like their official cloud images.