Which command line parameters are those and where in the app are they documented? I'm more than happy to "understand how the app works" if the means to do so are provided. All I could find is "these settings only affect the VR ON button", which doesn't tell me what is actually being done by the app.
I meant no offense by asking "what does the app do so I can undo it". I didn't ask this because I want to "blame" the app or whatever - to me it's just some app, I don't care. But I figured you might, since it's your app...? Is someone describing a problem they've encountered after running your app (coincidentally or not) not something you want to hear about?
Anyway, I'm still going to describe what happened to me, so that future people perhaps-coincidentally affected by the same issue can work it out. If you at any point think this has anything to do with your app, I'm happy to provide details, videos, logs, whatever, as the issue is still ongoing and I've now found a (to me, nonsensical) workaround. If you don't want to hear any of it because you're certain that it's just sheer coincidence, just ignore me. My intention here at this stage is to be constructive and to help others who may run into the same issue, not to attribute blame.
So, I installed the updater and used it to run DCS (standalone) in SteamVR mode. I did that as explained in the app, i.e. using the VR ON button with the dropdown in the settings page set to SteamVR. Everything worked as expected, i.e. DCS launched in SteamVR mode instead of Oculus. I made no other changes to my system as far as I can tell - no changes to Oculus settings, SteamVR settings, DCS in-game settings, etc. Had a perfectly working DCS standalone install up to that point, running in Oculus mode on a daily basis with no issues.
After that, I'm done with my little SteamVR experiment, so I don't need the app anymore. I shut it down and go back to launching DCS normally, without using the app (so nothing to do with the "VR ON" button). Then I realize I can no longer get DCS to start in Oculus mode. When I launch DCS (through my usual desktop shortcut), if VR is enabled in the options.lua OR forced through the command line, then DCS tries to launch in SteamVR mode, but fails to find a headset. If VR is disabled in the options.lua, or forced off through the command line, then DCS launches in 2D mode (as expected)
So at that point I start trying different things to fix it:
1) Run via the app again, setting the drop-down back to Oculus mode, and launching via the "VR ON" button again = no change (still launched DCS in SteamVR mode instead, with SteamVR failing to find a headset).
2) Full DCS cleanup + repair = no change
3) Renaming my saved games folder, to let DCS recreate all preferences from its defaults = no change
4) Switching my Quest 2 back and forth between link cable mode and airlink mode = no change
5) Uninstalling SteamVR = some change, in that DCS launches in 2D mode regardless of the options.lua and command line parameters (so again acting as if no headset was present).
What eventually fixed it:
Renaming my DCS folder (the actual install folder, not the Saved Games folder). After doing this, I could reinstall SteamVR, restore my old preferences, etc. Basically put everything back to normal, except my DCS folder is a different path. If I rename my DCS folder back to its original name, everything breaks again. So for now I have a perfectly working DCS install, as long as I don't rename it back to what it was. Makes no sense to me, but beats a broken install.