Twitter co-founder Jack Dorsey has been highly critical of Elon Musk for the way he has run the platform since its acquisition.

Asked if Musk is the best platform steward, Dorsey replied: “No. I also don’t believe he acted properly after realizing that the timing of the acquisition was unfortunate. I also don’t think the board should have forced the sale.”

“It all went wrong,” Dorsey wrote on Bluesky, an alternative platform he recently launched.

Dorsey, who has had a good relationship with Musk for years and who offered him a hand in the Twitter acquisition, has previously spoken publicly in support of the deal. And last year, he called Musk “the only solution.”

On Friday, user Bluesky said he was very sad how the acquisition ended, and Dorsey agreed. But Twitter “would never survive as a public company,” he added in another post. “Would you rather it be owned by hedge funds and Wall Street activists? It was the only alternative.”

Under Musk, Twitter’s staff was drastically reduced, and the platform has experienced a number of crises, most notably with user verification. Musk offered a Twitter subscription service where users could get a blue tick for $8 a month.

“Payment is a trap and I totally disagree with that,” Dorsey told Bluesky. “The payment systems used for this proof exclude millions, if not billions of people.”