This is not an intentional change in behavior and so there is no Custom option that would allow you to go back to the old behavior.
To clarify: the cause of the new and undesirable behavior that you are seeing is either a bug or misconfiguration on your end. Nobody would want that behavior. I did not implement that behavior. It just happens and everyone agrees that that is not good.
It is not possible to add an option to disable that undesirable behavior because it is unknown what is causing it. And even once it known what is causing the behavior it would not make sense to add an option, because then we could just fix the bug for everyone, instead adding an option to optionally do that.
In other words, something is wrong and you will have to figure out what it is. I recommend you start with
emacs -Q... and the other debugging tools described in the manual.