Ofc not, if anything Id say the contrary. I have plenty of Homebrew in my campaign (Im a DM but also a player). I mix canon/Lore with my own. The thing is I stated something was official lore/canon, (which it still is), he matter of factly dismissed that claim based on what he "knew" was official lore. Hence why I got triggered, because he was so obviously wrong.
If most Paladins follow/worship a deity, (at least some, maybe many being given powers/being uplifted to Paladin by that deity). Then its quite reasonable to say that just about all the paladins who follow a deity are given their powers from that deity. They are tied to an oath, if they break that oath, then those powers can be taken away. Who takes them away? The deity they follow naturally. Ofc, I will concede that the deity they worship might not be the only one feeding the powers. It might be the triad forexample as a whole (Pally worships 1 or all of them, and/but is given powers from all 3).
It does make sense that those paladins which do swear oaths to particular deities would lose a significant portion of their power if they broke their faith to that deity.
I see a few efficient solutions:
See if all Cleric of X tag statements can simply be transferred to Paladin and still make sense. Have the paladin just be a holy warrior equivalent of cleric, or have no deity.
OR
See if we can slightly alter all "Cleric of X" tag statements to fit EVERYONE as "Follower of X," where anyone can choose to follow a God or be an atheist and get some power out of it. Then, if Druids or Paladins disrespect their god, they lose a special ability, but can still have power through nature and oaths as representing drawing on a group of portfolios without a specific god.
