Not sure if this has been updated/changed since version 2.51.2, but you can:
document.querySelector('html').classList.add('__fb-dark-mode') into the console.And that should enable a decent dark theme.

This issue is fixed and merged into master. The fix will be available on next update (the one after 2.51.2 since that's the latest one). Regarding the quick fix, @Rozkipz is right. That's how we fixed it basically with minor patches.
Is there a way to open the console from the UI? The F12 keybinding is intercepted by my OS, and there doesn't seem to be an immediately obvious way to open it from the menu bar.
I think you should be able to open DevTools by right clicking anywhere on the app and clicking 'Inspect Element' menu option. That should then show DevTools window. Then just click on the 'Console' tab and the code from comments.
I'm not sure if this will work since I don't use a Mac but it works on Linux and Windows.
can't you do command+shift+c or command+shift+i
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This issue is fixed and merged into master. The fix will be available on next update (the one after 2.51.2 since that's the latest one). Regarding the quick fix, @Rozkipz is right. That's how we fixed it basically with minor patches.