He terminated the Bute House Agreement that had been in place since 2021 and with it, took away the two ministerial posts that had been allocated to the Greens.
It was to be his undoing. The Tories promptly called a vote of no confidence in the then first minister who, realising he had no chance of surviving, quit.
“I, frankly, f***** up,” Mr Yousaf later said.
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By that point, being part of the Scottish Government had become increasingly difficult for the Scottish Greens.
The SNP-led administration had scrapped climate targets, saying the ambition of cutting carbon emissions by 75% by 2030 compared to 1990 levels was out of reach and would need to be ditched.
Ministers had also paused the prescription of puberty blockers for under-18s following the Cass review, a decision, Mr Harvie said caused “distress” in the party.
Mr Yousaf’s decision to axe the agreement came days after the Greens announced that party members would be given a vote in the coming weeks on whether they should remain in the Scottish Government.
How would members have voted? We’ll never know. While some of the MSPs were confident activists would have backed staying in power with the SNP, there was a lot of anger from the grassroots.
And, unlike in other parties, the power lies with the grassroots far more than it does with the leadership.
That schism between the elected members and the party faithful was evident at the autumn conference in October when members voted down the agenda.
While Patrick Harvie and Lorna Slater, and other MSPs including Ross Greer and Gillian Mackay, voted to keep the original agenda in place, members gave them a bloody nose.
The Scottish Greens will be proud of a number of policies achieved while in government, but one of the big stories next year could be the court case around the deposit return scheme.
Biffa is currently suing the Scottish government for almost £170m over the collapse of the plans.
Last November, the firm claimed Ms Slater “negligently misrepresented” the chances of the Deposit Return Scheme succeeding.
The Court of Session heard that she gave the waste company a written assurance but did not mention that the scheme would need the final go-ahead from Westminster under the Internal Market Act.
The then Circular Economy Minister abandoned the botched project in June 2023, blaming the UK Government after ministers in Whitehall made clear the Scottish Government would only be given the necessary exemption to the UK Internal Market Act if they made substantial changes.
The row looks set to rumble on. The Greens are out of government, but will they avoid the fallout?