Essentially, despite owning a Minecraft Playstation 4 Edition Disc that, before it forces an update to Bedrock, boots up the earliest Legacy Console version of Minecraft PS4, when the update to bedrock finishes there is no editions button to go back. It brings up the many screenshots and explanation of what updating to bedrock adds, one screenshot even showing the editions button, but when it gets through it's explanation the button is just not there.

From what I can tell, those who bought Minecraft digitally bought the Bedrock Edition and as such are not entitled to the Legacy version, that much makes sense. However, I am using a physical copy of the Legacy version, and under that logic I instead should not be entitled to Bedrock as they're separate games. Still, I am unable to play the game that I purchased, and any attempts to get help through support either result in silence or a community member who has no control over the situation.

This would not be a problem if we were able to easily purchase the game separately so as to experience the features we lost in the switch to Bedrock, or if the game could just check what disc is in the system to know whether or not to show the button. 

The other issues that I checked seemed to be related to the digital version, and them not having the button simply because they purchased Bedrock from the store following the cut off date. However, I am stressing that this is an issue of using the disc and not having a button, this issue existing for multiple updates by now and not having been fixed in any of them, yet being a very big issue as it prevents the playing of the game I actually purchased.

If these details effect anything:
I am playing on the Playstation 5.
I have previously purchased the game from the Playstation store, however I have since uninstalled that and attempted to use the disc version.