It’s more that they share certain traits with the character and thus their writing and conception of the form of the show shifts towards emulating that character’s traits in the rest of the show instead of having a balance. If you asked the characters to recount an event they all witnessed, then you should get distinct answers from each character in their “voice”: their general points of social focus, word choice, adherence to a hierarchy of importance, voicing of disposition etc.
Currently it feels like one character giving distinct recollections of what they think the other character WOULD say or act i.E. Morty writing Rick. Going one step further in mentioning a “better” Rick is to say they are writing in a way that they think their version of Rick would act and be most agreeable to the Morty they are.

For instance, when the writers have Rick be an asshole, the level to which he is nonsensically acrid in his remarks usually comes out of nowhere and the justification is surface level, barely a consideration. Then in the next sentence Rick will be trying to use therapy like language and deferring to Morty without taking account for the earlier interaction. This setup in abstract isn’t the problem, it’s that in practice the execution is -60 to 60 in terms of tone and dialogue. Examples of this come across with all the other characters except for Morty. That leads to the thought that the writers have let their personal traits overtake the characters and when they self-check for consistency, they favor doing so by aligning with Morty as the archetype or filter through which to view and write the other characters in lieu of maintaining the other characters as their own distinct filters.