Hey, it's definitely possible in Godot 4, but we did make some changes when porting the game from godot 3 to godot 4.
The main difference is that rather than adding a lot of collision shapes to a single area via the physics server, we are now adding separate area instances with , so the bullets now apply their transform to their registered area id rather than a shape.
Kind of like this:
As of it being necessary, can't say for sure as Godot4 introduced a ton of performance improvements (this implementation will probably still run way faster, but it may or may not be necessary depending on your particular use case).
I'd say give it a try, specially if you wanna learn a bit more on how the physics server works, and the extra performance will definitely not hurt!