G: [Non-text content: thoughts; content_type=thoughts]

G: [Non-text content: reasoning_recap; content_type=reasoning_recap]

G: I checked current reports. There are a few user reports of rotation failing across multiple apps after iOS 26.6/26.6.x, including YouTube, but I’m not finding evidence that this has become a clearly widespread or Apple-acknowledged 26.6.2 bug. Apple’s notes for 26.6.2 mention a cellular-update fix, not screen rotation. citeturn0search0turn0reddit19

So your instinct to check whether you accidentally hit the lock is the right first move.

Swipe down from the upper-right corner of your iPhone to open Control Center. Look for the button that looks like a padlock surrounded by a circular arrow: 🔒↻. If it is highlighted/red, Portrait Orientation Lock is ON. Tap it once to turn it off. Apple confirms that's the system-wide rotation control. citeturn0search1turn0search3

Then try rotating YouTube or the game again. YouTube also has its own setting under YouTube → profile picture → Settings → General → Rotate screen, although that wouldn't explain the game simultaneously failing—which is why the iPhone's orientation lock is much more suspicious here. citeturn0search2

If the lock is already off, there's a very useful diagnostic: open Measure → Level and physically rotate the phone. If the level responds normally, the phone's motion sensors are detecting rotation and we're probably dealing with a software/rotation-state problem. Apple specifically recommends this test when rotation isn't working. citeturn0search3

So I'd check the 🔒↻ button first. Given that two unrelated rotation-capable apps stopped rotating, that's the simplest explanation by a considerable margin.

G: [Non-text content: thoughts; content_type=thoughts]

G: [Non-text content: reasoning_recap; content_type=reasoning_recap]

G: That narrows it down substantially. If Orientation Lock is off and Level reacts correctly, the phone is detecting its physical orientation. That makes a dead accelerometer/gyro quite unlikely. Apple actually uses the Level test as its diagnostic step for exactly this situation. citeturn0search5

And I found something more relevant than what I found on the first pass: there are other iOS 26 users reporting essentially your exact symptom. One July/August report describes multiple unrelated apps—including YouTube, Safari, Photos, and Brave—refusing to rotate while Measure/Level and the camera still correctly detect orientation. Another user specifically replied that it began for them with 26.6. citeturn0reddit33 There are also older iOS 26 reports where the Control Center switch said rotation was unlocked but iOS behaved as though it remained locked; restarting cleared it. citeturn0search3turn0search15

So I'd now do this in a very specific order:

1. Test Safari itself. Open a normal webpage and turn the phone sideways. Apple specifically recommends Safari as a known rotation-capable test app. citeturn0search5
2. If Safari also refuses to rotate, don't bother troubleshooting YouTube or the game individually. We've demonstrated that the failure is at the iOS level.
3. Restart the iPhone. A normal shutdown/restart is enough for the first attempt. Apple explicitly recommends a restart after the orientation/Level checks. citeturn0search5
4. After restarting, test Safari before reopening YouTube or the game.

There's an interesting diagnostic distinction here: Level working tells us the sensor layer is saying “the phone has turned,” while several apps failing to rotate suggests the UI/orientation layer isn't acting on that information. That's remarkably close to the reports I just found.

So try Safari → rotate right now. If Safari doesn't rotate either, I'd call this a stuck iOS rotation state and reboot it rather than changing any more settings.

G: Yes—that's a good analogy for what the evidence points toward.

The important combination is:

motion sensors working + orientation lock off + multiple unrelated apps (including Safari) all stuck in the same orientation.

That looks much more like iOS's orientation-handling state has gotten stuck than an individual app problem or a hardware sensor failure. In old-PC terms, it's quite like a driver/service having the correct hardware information available but some higher-level state getting wedged and no longer propagating the “hey, orientation changed” event correctly.

I wouldn't worry about leaving it overnight, either. If everything else works, there's no particular reason this needs an emergency reboot. When you restart tomorrow, I'd expect that to be the most likely thing to clear the stuck state. If it survives a full restart, then it becomes interesting again, because we'd have ruled out the transient-state explanation.