[BUG]: macOS/Metal FullscreenUI pause background intermittently receives an extra scrim pass

[AlexanderZhk]

Describe the Bug

On macOS 26.4.1 (Apple M4, official notarized x86_64 build under Rosetta, Metal renderer), PCSX2's FullscreenUI pause menu intermittently blinks between two background brightness states across multiple games. The foreground Resume Game menu, clock, and status bars remain stable; only the frozen game backing changes.

This occurs in a maximized embedded main window (RenderToSeparateWindow=false), not exclusive fullscreen.

Comparing the two captured states shows that the darker frame is consistent with applying PCSX2's dark-theme pause scrim (#212121, alpha 200) one additional time. The FullscreenUI foreground and bottom status areas remain unchanged. This points to the game backing being dimmed twice or an already-composited frame being reused, rather than panel, VRR, or global-brightness flicker.

Relevant source:

• Pause scrim at alpha 200
• Dark-theme background color #212121

The behavior has occurred in multiple games, so it does not appear to be game-specific. The analyzed captures are from WRC Rally Evolved (PAL). I have not yet reproduced this on a fresh default configuration or a newer binary.

Reproduction Steps

1. Start any affected PS2 game in the official macOS build using the Metal renderer.
2. Keep rendering embedded in the main window and maximize the window.
3. Press Escape to open PCSX2's Resume Game FullscreenUI pause menu.
4. Leave the menu open.
5. The frozen game background intermittently switches between a brighter and much darker state while the pause-menu foreground remains constant.

This has occurred in multiple games and is intermittent. The analyzed captures came from WRC Rally Evolved (PAL).

Expected Behavior

The paused game background should remain frozen with one stable dimming scrim. FullscreenUI should not reapply its scrim or reuse an already-composited pause frame.

PCSX2 Revision

v2.7.386 (reproduced); v2.7.463 source checked, newer binary not retested

Operating System

macOS 26 (Tahoe)

If Linux - Specify Distro

No response

Logs & Dumps

No PCSX2, Metal, AGX, GPU, or WindowServer errors were observed while the brightness changes occurred.

System/display:

• MacBook Pro Mac16,1
• Apple M4, 24 GB RAM
• macOS 26.4.1 (25E253)
• Built-in Liquid Retina XDR display, 120 Hz
• Metal renderer, VSync enabled
• PAL guest: 50 FPS/VPS

Video:

PCSX2-pause-blink-ISO-GitHub.mp4

[TellowKrinkle]

If you meant to upload captures, I don't see any.

You can take a video screen capture of the issue with Shift+Command+5.

[AlexanderZhk]

@TellowKrinkle Here is a video capture showing the issue:

PCSX2-pause-blink-ISO-GitHub.mp4

[TellowKrinkle]

Can you run this file (unzip it and drag the .gs or .gs.xz file onto the PCSX2 window to run it) and check if you can reproduce the issue with it as well?

(And just to make sure, it starts flashing immediately without needing to wait, or does it require waiting for more than a few seconds?)

[AlexanderZhk]

Can you run this file (unzip it and drag the .gs or .gs.xz file onto the PCSX2 window to run it) and check if you can reproduce the issue with it as well?

(And just to make sure, it starts flashing immediately without needing to wait, or does it require waiting for more than a few seconds?)

No flashing with this executable initially and in a 10 minute period of having it full-screen and periodically entering the pause menu.

[TellowKrinkle]

Can you take a GSdump of WRC (Tools → Save Single Frame GS Dump), then play it back and see if it also has the issue? If it does, zip the GSdump and upload it here.

[AlexanderZhk]

I created and replayed a WRC single-frame GS dump on macOS.

The original FullscreenUI pause-background blink is not present during GS-dump playback. However, the rendered game image itself alternates between a brighter and darker state during playback.

The same game-image blinking occurs with both the Metal and Software renderers, so this particular behavior is not Metal-specific.

Attached are the zipped GS dump and representative bright/dark screenshots.

GS dump

WRC-Rally-Evolved-GSdump.zip

Bright state

Dark state

[AlexanderZhk]

I reproduced the same FullscreenUI pause-background blinking in Resident Evil: Dead Aim (SLUS-20669) using PCSX2 v2.7.492 with the Metal renderer.

While the pause menu remains open, the game background continuously alternates between darker and brighter states. The pause-menu foreground and bottom status bar remain stable.

This game runs at 60 FPS/VPS, so the issue is not specific to WRC Rally Evolved or PAL/50 Hz.

I have attached a single-frame GS dump captured from the affected Resident Evil scene.

GS dump:

Resident-Evil-Dead-Aim-SLUS-20669-GSdump.zip

Dark state:

Bright state:

[AlexanderZhk]

Additional timing clue: the issue reproduced continuously in Bully on PCSX2 v2.7.492 using Metal, further confirming that it is not game-specific.

At the time, the PCSX2 process had been running for about 25 days and the VM had remained paused for roughly 40 hours. It went through multiple macOS sleep/wake and dark-wake cycles during that period. The problem may therefore require a long session—possibly 10+ hours—or a substantial amount of time on the PCSX2 pause screen.

PCSX2 was using about 106 MB RSS, and its log contained no Metal device-loss, graphics-failure, or out-of-memory errors. This makes a long-lived paused presentation state across sleep/wake, display, or Space transitions a stronger candidate than ordinary memory growth.

Possibly related reports:

• #11178 documents macOS fullscreen behavior changing depending on whether the fullscreen window is visible in the current Space.
• #13504 is a different pause-background flicker affecting a hardware-renderer case.
• #14801 and its proposed fix #14841 concern another macOS fullscreen/window-lifecycle regression.