My guess is that the "real presidents" of the Biden administration -Jill, Hunter, a couple staffers- wound up so at odds with Kamala, they no longer agreed to the plan.
Kamala, equal parts incompetent and egotistical, gambled on making an end run around them, probably threatening to leak specifics on who was really running the show. Joey's decline in mental faculties damages the party was a whole, but leaking that it is really unelected family members calling the shots damages the Biden brand.
Frankly, there should be impeachments all around on this one. Dems have already laid precedent that a former president can be impeached.