Godot 3.5 to Godot 4 Migration - C7-Game/Prototype GitHub Wiki
Textures no longer rendered with nearest filtering by default, causing lots of textures to render incorrectly in Godot 4. Fixed by selecting project -> project settings -> (rendering / textures / canvas textures / default texture filter) -> nearest
CanvasItem.Update is now CanvasItem.QueueRedraw: godot forum link
SetInputHandled is now a method of ViewPort: reddit link
QuadMesh was merged into the PlaneMesh class (pr), and PlaneMesh.Orientation must be set to PlaneMesh.OrientationEnum.Z to face the Z axis, otherwise it will not display (C7 map lies on the XY plane)