Hey @Samsung_Fq5kd9O, I hope you are doing well.
Once you start recording, it is normal behavior for the toggle to go away while in the stock camera app. This has been that way since the device was released. Other third party apps such as Snapchat do however support changing the camera while recording.
If you'd like, I can request that a moderator marks this post as a feature request. I feel that this would be helpful.
Have a great rest of your day!