Did you not see the video?
As far as fbx cutting UV seams its been documented since 4.27 and has been an issue since.
Skeletal mesh importer cuts mesh over UV seams - Development / Rendering - Epic Developer Community Forums (unrealengine.com)
Shadows broken in VR - (which I’ve branched a shaders directory from main and upkept every hotfix regression)
UE5.4 (and 5.4.1) shadows are broken in VR (VR Template, default settings) - General / Issues and Bug Reporting - Epic Developer Community Forums (unrealengine.com)
Pixel Streaming Memory Leaks - (Which I committed a PR for and it regressed after stomping from a fortnite merge.)
memory leaks in pixel streaming(5.21) - Programming & Scripting / Multiplayer & Networking - Epic Developer Community Forums (unrealengine.com)
UE 5.2.1 Pixel Streaming performance problem - Development / Platform & Builds - Epic Developer Community Forums (unrealengine.com)
Enhanced Input Local Multiplayer issues
5.1 local multiplayer not working - Development / Getting Started & Setup - Epic Developer Community Forums (unrealengine.com)
Level Blueprint variable panel request (5+ years and counting)
[Question] About Level Blueprint variable - Development / Programming & Scripting - Epic Developer Community Forums (unrealengine.com)
At the end of they day there are 1.9k PRs open against the unreal engine repo. There are just as many bug reports / tickets covering CORE features and issues… yet instead of saying hey we fixed something that used to work in UE4 and broke in UE5 (VR instanced stereo, online subsystems interface actually working with steam, OpenXR, steam input, Enhanced input system and local player functionality / context assignment, FBX stability, Physics performance and stability, a functional and reliable replication and NETGUID seamless travel behavior, paper2d and 2D workflow support) … we get substrate and megalights and a ton of other film and non core related experimental features and developers still needing to rely on AdvancedSessions for a “use lobbies bool” that should have been added to the standard session node years ago. We are still working with a 2D workflow that has been considered experimental/beta since 4.3 in 2014. I “personally” don’t really care too much about BP support because for me it’s easy to just expand via bp libraries or subsystems to help the community and fix things or add PRs back to plugins like Advanced Sessions. However epic hails BPs as its scripting language and 99% of unreal devs (many of which I support) start out in BP and it still cannot be used to the capacity for server travel or joining a “lobby session” or many other rather simple core features… and guess what!!! We have UEFN and verse now!!! … When in my opinion BPs aren’t even kept to the standard they should be (destroyed data assets and structs anyone?) At some point you just gotta start asking why and giving some tough love feedback.
uno1982/UE4.27_OnlineSubsystemSteamFix: Fix to issues with UE4.27.2 binary engine module (github.com)
Please don’t take anything here the wrong way as again… I LOVE this engine and I’m actively attempting to document fix or provide paths to take to work around most of these things. It’s just exhausting taking 2 steps back for every step forward.