Some third party apps will only work horizontally on the screen as it's embedded in the app, @ready2rock. Having this turned off won't affect these apps.
I've just checked this on the Galaxy S23+ and the Galaxy S22 Ultra, and some third party apps do rotate while the phone is set to portrait mode. If it's happening with a specific app that didn't rotate but rotates on your S24 Plus, please send an Error report within 15 minutes after this is replicated. You can do this by going into the Members app > Support > Error reports.
