Unless there was evidence you had not underestimated but were, e.g., getting a kickback on the cloud costs that you deliverately lowballed in your estimates, they might fire you, but they almost certainly wouldn't put out a press release about it being for your failure to be candid.
That language indicates that the board has a strong belief that there was a major lie to the board or an ongoing pattern of systematic misrepresentation, or a combination.