Dear developers, here's the list of some unknown/known issues. It would be great to see fixes in the near future.
List of issues:
[Sync] random colours of vehicles are sometimes desynced - proven by [WS]Teddy
[Client] Player.WeaponAmmo doesn't update every shot, but only on weapon change
[Client] setting Player.Health to 0 crashes the client
[Server] LU doesn't load custom LU/data/weapons.dat
[Server] Crashes when use modded handling.cfg in LU/data/handling.cfg
[Server] Colour class returns only R value
[Client] GetHUDItemEnabled doesn't return right bool
[Client] game crashes with modded cars (GTA3.IMG, DFF vs Sync = Crash)
[Client] starting chat typing 'T' and pressing TAB is causing a crash.
[Client] objects disappears on explosions or reconnect
[Client] onClientClickButton doesn't work
[Client] onClientClickCheckbox should return checkbox pointer instead of ID
List of requests:
[Server/Client] new Player.Marker param to show someones marker only for team or Blip.AttachToEntity
[Server] loading custom timecyc.dat
[Server] new part reason: PARTREASON_RECONNECT
[Sync] foot/vehicle sync improvements
[Client] make CRC checks harder to bypass
[Client] disable debuggers and memory scanners
[Server] Fix WeaponAmmo
Feel free to post your issues here, I'll be updating this OP.