[p5.js 2.0 Bug Report]: Instanced p5.strands shader doesn't work after first frame if you use only it

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• WebGL
• Build process
• Unit testing
• Internationalization
• Friendly errors
• Other (specify if possible)

p5.js version

2.1.2

Web browser and version

Firefox

Operating system

MacOS

Steps to reproduce this

Steps:

1. Create a model using buildGeometry so that we can draw it with an instance count
2. Create a p5.strands shader that offsets position based on the instance number
3. Draw a number of instances using the shader

It flickers showing all the instances, and then goes back to just showing one:

But weirdly, if you switch to using another shader in the same frame, e.g. by doing the instanced rendering within a push() and pop() and then drawing another shape without a custom shader, then all the instances show up like they're supposed to:

Snippet:

let instanceShader
let instance

function setup() {
  createCanvas(400, 400, WEBGL)
  
  instanceShader = baseMaterialShader().modify(() => {
    getWorldInputs((inputs) => {
      inputs.position.x += (instanceID() - 2) * 50
      return inputs
    })
  })
  
  instance = buildGeometry(() => sphere(20))
}

function draw() {
  background(220)
  
  push()
  noStroke()
  shader(instanceShader)
  model(instance, 5)
  pop()
  
  // Works when you uncomment this?
  // push()
  // sphere(20)
  // pop()
}

Live: https://editor.p5js.org/davepagurek/sketches/4pTh3thfJ

Reproduce the issue with the linked live sketch and the provided buildGeometry, baseMaterialShader, instanceID, and model calls. Start by tracing the WebGL instanced rendering and shader behavior across frames; done means the five instances remain visible when only the custom p5.strands shader is used, without the push/pop workaround.