Self-view video forced to portrait in iPad Safari (also occurs on GoogleMeet)

Despite using the iPad in landscape mode, self-camera video is forced to portrait (Rotate 90 degrees). Only the video is portrait, even though the browser is in landscape orientation.

Our app use getUserMedia() to get the video.

The problem also happend in iPad Safari GoogleMeet.

Details:

• The problem occurs even when the screen orientation is locked.

• After the video has been forced to portrait, rotating the iPad temporarily changes the video to landscape, but forces it to portrait again.

• It takes around 0 - 30 seconds before the video is forced to portrait.

• Both selfie camera and back camera

I have confirmed this problem on the following devices

• iPad 8th iPadOS: 18.3.1
• iPad10th iPadOS:18.3.1
• iPadPro(M4) iPadOS:18.3.1

Some devices do not have this problem, even if they are the same model and OS version.

I have tried the following

• restart
• factory reset
• Configuration changes (Settings > Apps > Safari)
  • SETTINGS FOR WEBSITES
    • Camera > Allow, Ask
    • Microphone > Allow, Ask
  • Advanced ＞ Feature Flags
    • Reset All to Defaults
    • Screen Orientation API (Locking / Unlocking)
    • Screen Orientation API
    • WebRTC AV1 codec

Please help me to resolve this problom. Thanks.