the founder is on a vesting schedule set with the vc. walking away forfeits his ownership in the company (not sure of the specifics of this weird deal, but this is true in 99% of situations) which returns his ownership to the VCs either directly or functionally.

the only reason he'd walk away is because he thinks other opportunities are higher EV. if he believes this, a) the investors investment is likely worth virtually 0 anyway and b) if it's not, removing a leader who doesn't want to be there probably increases P(success) for the company and further increases the value of the investment.

founder departure isn't good for the narrative, but it's a symptom of an investment going bad, not often a cause.