In the Star Trek: Next Generation Technical Manual, it is mentioned that the Bridge module is replaceable. Memory Alpha also says bridge modules are replaceable:
https://memory-alpha.fandom.com/wiki/Bridge#Background_information_2 although I don't know where the canon source is for this (it's not listed in the article).
So how come many are insisting the Cage bridge and Discovery Enterprise bridge are the same bridge? The module explanation was provided decades ago to explain changing bridges, how come fewer people seem to accept it now? If the module explanation worked before, logic would indicate it would work in this instance too. That's the entire reason the explanation was created to begin with.