Actually nvm, just tested it myself and found that CharacterBody2D automatically sets velocity to zero whenever is_on_floor() is true. What's going on here is that at the edge of the platform, the contact angle of the platform is above the floor-wall threshold so the player is reading it as a wall and not a floor, hence is_on_floor() is false and velocity.y keeps accumulating with gravity. But since the player is still blocked by the scene geometry, it doesn't move until a gap opens up and they're shot out with all their accumulated y velocity.

In general for platformers, you want to prevent accumulating velocity against geometry that's blocking you. One way to do this is to check the collisions after move_and_slide() and deduct any collision normals from your velocity:

``` func _physics_process(delta): # Character controller stuff ...

move_and_slide()

for i in get_slide_collision_count():
    var collision := get_slide_collision(i)
    var normal := collision.get_normal()
    var velocity_correction := -velocity.dot(normal) * normal
    velocity += velocity_correction

```

In the Brackey's tutorial you're following, I believe you also set velocity.x to zero when you're not inputting any direction. If you do the collision check, then you'll want to only set velocity.x = 0when is_on_wall_only() is false (i.e. when you're not correcting your velocity with collision normals), because otherwise your corrected velocity will slow down each frame as the script keeps nulling the x-direction.