3DS display feature "2D (Pixel Grid Effect)" no longer functions as of 1.22.0 up to current

Is there an existing issue for this?

• This is a bug in RetroArch frontend
• I have searched the existing issues

Description

3DS builds of RetroArch have an option under the "User Interface" tab to control how the 3D components of the display are used. One of these modes, "2D (Pixel Grid Effect)", was functional in release version 1.21.0 but appears to be broken as of 1.22.0. The issue appears to have persisted up to the current 1.22.2, including a nightly build from late May 2026.

Expected behavior

When working, this display mode should appear to turn on the display's 3D mode, but still appear as a flat, stable 2D image, only having the noticeable "grid" effect seen when 3D mode is activated. As of 1.22.0, switching to this mode no longer changes the display mode from 2D (therefore no pixel grid effect), nor does the 3D slider toggle the mode when it is set.

In some cases I have seen 3D mode be enabled going between cores/games, but the effect is still broken in these cases. In this state, the display still has its parallax separation enabled (the only display mode this should be present in is the full "3D" option) and the 3D indicator on o3DS remains unlit.

Steps to reproduce the bug

1. Go to "Settings" > "User Interface"
2. Set "3D Display Mode" to "2D (Pixel Grid Effect)"

Version/Commit

1.22.0 (Git 703321e)

Bisect Results

1.22.0 stable

Present in the nightly version

I don't know

Platform & operating system

3ds (ctr)

Affected Cores

No response

Environment information

Hardware: Old 3DS (CTR-001)
System Software: v11.17 (luma cfw)
Display Driver: ctr

Relevant log output

Reproduce the issue on an Old 3DS using Settings > User Interface and the ctr display driver, comparing 1.21.0 with 1.22.0 or later. Done means selecting “2D (Pixel Grid Effect)” enables the display’s 3D mode without parallax separation, shows the pixel-grid effect, and responds correctly to the 3D slider.