There’s a lack of automated code testing which could filter out many of the problems before release, bugs which instead have been with the engine for 10 years now. They’re part of the literal million reports that just sit there post the bug reporter process.
Modularity of the engine could also be improved. Many new features are created as plugins (good!!!) but are pushed to developers as replacements for the “old” systems (common UI, Enhanced Input vs Slate), deprecating “old” features with alpha / beta ones. The developers turn into beta testers and newcomers to the engine don’t realize that they’re still working with the “old” system in new clothes. that is toxic to devs who have been with the engine for a long time and looks more like a marketing move. At the same time, the old systems (character movement component, Slate and others) can be a tangled mess which should be refactored. Possibly as plugins as well.
With a high level of modularity LTS doesn’t need to stall development of new features. Unfixed engine bugs are what takes up so much time in every new version. New features can all be made truly optional. Meaning: if it’s not “checked” on the “plugin list”, their files don’t even have to be on your PC. Currently it’s such a mess. All that experimental data you don’t use most of even after 10 years of being a dev on it. Developers can create plugins at high speed especially if they don’t have to deal with engine dependencies and engine bugs. And if they are truly optional, no one on the LTS version will be bothered with the alpha / beta stuff. On the EPIC launcher you’d get a UE5 LTS (minor versions are just fixes), and an additional list of experimental addons branching off to whatever they got in mind.