
The issues that may need your attention are:
- The new version comes with an iframed editor that can affect custom editor code.
- As usual you need to update your older plugins/themes especially abandoned plugins and custom PHP.
- Custom Gutenberg blocks may need testing.
- Custom admin screens may need CSS/JS adjustments because of continuing admin design-system changes.
- Don’t assume that the Page-builder sites aren’t automatically “safer.” WPBakery, Elementor, and GenerateBlocks need to be tested against the new Core rather than assuming compatibility. So test-run the entire website for compatibility issues.