One of the hottest debates: Unlisted components. The 2022 PDF dramatically limits the use of unlisted (general purpose) components in a UL 508A listed panel. Unless a component is specifically "Recognized" (RU mark) or "Listed" (UL mark), it is much harder to justify its inclusion without a field inspection.
Ironically, the "hot" keyword is literal here. The 2022 edition updates the temperature rise limits for bus bars in high-density panels. With the push for smaller enclosures and more components, heat rise testing (or the calculation method) has been revised. Ignoring this could lead to a failed temperature test and a melted wireway. ul 508a 2022 pdf hot
For the first time in years, the rules for determining the Short-Circuit Current Rating of a panel have changed significantly. Panels that previously passed muster may now require additional current-limiting devices. This has engineers scrambling to re-run calculations and update nameplates. One of the hottest debates: Unlisted components