Regression: (seizure risk?) screen flickers rapidly when using tracy

[aevyrie]

Running the scene viewer with caldera hotel (only tested on Mac) flickers violently when using the trace-tracy feature.

Minimal Repro

cargo run --example bloom_3d --features=trace_tracy

[mockersf]

I could not reproduce on my mac with cargo run --example load_gltf --features trace_tracy or many_foxes

[aevyrie]

it seems to happen on more challenging scenes, like caldera.

[mockersf]

I can reproduce on https://github.com/DGriffin91/bevy_caldera_scene

On that scene if I don't enable Bloom and ScreenSpaceAmbientOcclusion, it doesn't flicker even with bevy/trace_tracy enabled

[alice-i-cecile]

I think that this is likely due to the bug with schedule ordering that we fixed post 0.18.rc-1: #21930. This sounds like a critical system ordering is getting screwed up, but only when the scheduler is under enough load to actually trigger a flip-flop.

It would be good to try and reproduce this bug again.

[mockersf]

It doesn't need real load, just rendering passes. It can be reproduced on the bloom_3d example

[aevyrie]

I had griffin's bistro repo all set up to point to my local bevy files and retested on main, still seeing the awful flashing.

WARNING: FLASHING/STROBING LIGHTS

Screen.Recording.2026-01-01.at.10.27.35.AM.mov