The event horizon is not a solid surface but a boundary in space-time.

Unlike a wall or surface you can touch, the event horizon is an invisible boundary in the fabric of space and time. It’s defined by how gravity bends space-time so much that light paths curve back in. This means that from the outside, the event horizon looks like a point where light and matter vanish. But if you were falling in, you wouldn’t feel a sudden wall — instead, you’d cross this boundary without noticing it immediately.