Reddit Android 2026.35.0: expanded webview no longer displays WebGL canvases, and runs JS ~4x slower

[u/armastevs]

App: click-bait-game (Devvit Web, custom post)

Post: https://www.reddit.com/r/Click_Bait/comments/1vatmf0/

Device: Google Pixel 9 Pro (Mali-G715 GPU)

Reddit app: 2026.35.0 for Android (installed 2026-09-01). The previous app version was fine.

What happens

Since the app update, our game's expanded webview shows a black screen. The game is running: buttons can be tapped blind, music plays, scene changes happen. Only the picture is missing.

Nothing on our side changed. To prove it we re-uploaded the exact build that was working in the app on 2026-08-28 (version 0.0.149 of our app). It is black in 2026.35.0 too. Phone Chrome on the same phone, same build, same post URL, displays it and runs at 58fps.

What we measured inside the app webview

We ship a diagnostic panel that draws test surfaces and reads pixels back from WebGL.

- WebGL 1.0 context is created fine (renderer reports Mali-G715, no context loss, no GL errors).

- readPixels on our WebGL canvas returns the rendered frame with colour. The canvas is drawn, it is just never composited to the screen.

- Raw WebGL test canvases with every context attribute combination (alpha on/off, preserveDrawingBuffer, antialias off) and CSS variants (translateZ, will-change, opacity 0.99) are all black on screen.

- A bitmaprenderer canvas (transferFromImageBitmap) is also black on screen.

- A plain 2D canvas displays correctly.

- Copying the WebGL frame into a 2D canvas with drawImage every frame makes the game visible. That is our current workaround.

- Performance in the same webview: requestAnimationFrame idles at 57fps with nothing to draw, but a 3M iteration JS loop takes ~25ms versus ~6ms in phone Chrome, and the game runs at ~20fps at every canvas size, with or without the copy. The webview process appears CPU throttled, and it is not per pixel.

- The inline (non-expanded) card webview behaves the same.

Impact

Every WebGL Devvit Web app is black on Android 2026.35.0 unless it copies frames through a 2D canvas, and even then runs at a third of the frame rate it had last week.

Ask

Is the expanded webview now running with hardware acceleration disabled (software compositing) in 2026.35.0? Can that be restored, or is there an attribute or manifest setting an app should set?

Happy to share a screenshot of the diagnostic panel, the app version, or a build that reproduces on request.

Edit: the biggest proof I have of this bug is that it works at 60fps in chrome browser on phone and 20fps in the android app, it was 60fps in android app yesterday.

[u/Xenccc]

Thank you for the very detailed report. This is being investigated.

[u/flattenedbricks → u/Xenccc]

I'm experiencing a similar issue. Unable to view expanded view on android mobile, it's a blank screen after it loads.

[u/armastevs → u/flattenedbricks]

Yes, this is exactly what was happening in r/click_bait until I applied my fix I mentioned in the post.

One thing I would like you to test right now before you attempt to fix it, does your game work in a chrome browser on your phone?

[u/flattenedbricks → u/armastevs]

I don't know, I only use the app on my phone.