Ubuntu has a long history of shipping preinstalled Ubuntu Desktop laptops and workstations with many OEMs (e.g. Dell, HP, Lenovo to name drop a few in alphabetical order). This has been made possible due to the extensive engineering efforts of the Canonical Kernel Team to introduce support for bleeding-edge hardware, and to create bespoke kernel flavours on the LTS releases. However, prior to Ubuntu 20.04 LTS one typically had to keep the preinstalled version of Ubuntu that came with the machine, or to install using bespoke per-SKU Ubuntu Desktop OEM installation media.
Furthermore, in the past there were behavioural differences between .0, .1 & .2+ installation media, such that installations using .0 and .1 media resulted in different hardware support than installations made using .2+ media.
For the Ubuntu 20.04 LTS development cycle, the Desktop, Certification, and Foundations teams made an engineering effort to unify the installation experience that results from using any version of the Desktop installation media.
Subsequently, when using any Ubuntu Desktop 20.04 LTS installation medium the best kernel for your hardware is chosen and installed automatically. Additionally, once your hardware is fully supported and certified in a newer version of the hardware enablement kernel, your system is automatically rolled and switched from the OEM kernel to the HWE kernel. Ubuntu recommends to stay on track with the kernel flavour chosen by the installer. Manually changing to other available kernel flavours may result in degradation of performance and lack of support for certified hardware.
The in-archive switch from v5.4 to v5.8 coincided with a CRD (coordinated release date) for several security vulnerabilities. And while automated testing passed for all drivers, we now know that at least three tests returned false positives (tests reporting a pass, while in fact failing). Our mistake has been identified, the tests rectified, and fixes for three[1,2,3] of the kernel bugs have already been rolled out in Ubuntu 20.04 LTS. Unfortunately, rolling the kernels back was not an option due to the fixes for security vulnerabilities.
We hope this update explains the installer changes that were designed and implemented between Ubuntu 18.04 LTS and Ubuntu 20.04 LTS, which are now bearing tangible benefits.