Firefox Shift+click shows incognito indicator but doesn't open private browsing

[meltyli]

Describe the bug

When selecting a Firefox profile while holding Shift, Browsers displays the incognito/private browsing indicator, but Firefox does not actually open in private browsing mode.

For example, I have the following Firefox profiles configured:

"profile_order": [
  "/usr/lib/firefox/firefox#Private",
  "/usr/lib/firefox/firefox#Normal",
  "brave#Default"
]

If I select Normal normally, it opens the expected Firefox profile.

If I hold Shift while selecting Normal, Browsers shows the incognito indicator as expected, but Firefox still opens a normal, non-private window.

Brave works correctly: holding Shift while selecting my brave#Default profile does open a Brave incognito window. This suggests that the Shift/incognito functionality in Browsers is working, and the issue appears to be specific to how Firefox is launched.

The Firefox profile itself is also opened correctly; the issue is specifically that the private/incognito mode is not applied.

I have not investigated or tested a source-level fix, so I'm not sure whether this is related to the Firefox command-line arguments or something else in the Firefox launch implementation.

System

• OS: CachyOS
• Browsers Version: 0.7.3-1 (via AUR)

Expected behavior

Holding Shift while selecting a Firefox profile should launch that profile in a private browsing window, just as it does for Brave.

Actual behavior

The incognito indicator is displayed in Browsers, but Firefox launches normally rather than in private browsing mode.

[liias]

Firefox version?

[meltyli]

Name Firefox
Version 154.0.1
Build ID 20260825192222
Distribution ID archlinux
User Agent Mozilla/5.0 (X11; Linux x86_64; rv:154.0) Gecko/20100101 Firefox/154.0