The Bute House Agreement was not signed until August 2021, which meant that for three months after the May 2021 election, the SNP continued with what was billed as a "minority government". That was technically inaccurate language, because excluding the non-voting Presiding Officer, there were 64 SNP MSPs and 64 MSPs from all other parties combined. It was therefore impossible to bring down the government as long as all of the SNP MSPs turned up. A tied vote on a motion of no-confidence would simply have led to the Presiding Officer using her casting vote to defeat the motion, in line with convention.
However by breaking off the Bute House Agreement today, Yousaf is not reverting to that status quo ante, and the reason is Ash Regan's defection last autumn from the SNP to Alba. There are now five opposition parties in the Scottish Parliament, and they outnumber the SNP by 65 seats to 63. So in theory the government can be brought down, but in practice I struggle to imagine the Greens risking the wrath of the independence movement by "doing a 1979" by bringing about an election at such an unfavourable moment.
However, the Greens now seem to hate Yousaf's guts far more than Alba do, which would have seemed an impossible state of affairs only yesterday. It seems almost inevitable, then, that they will find specific issues on which to vote with the unionist parties on, and the only way in which Yousaf will avoid defeat is with Ash Regan's vote. (Remember the convention on how the Presiding Officer breaks a tie will not always work in the government's favour - it's about backing whatever is the status quo, not about automatically backing the government line.)
This is, then, kind of the arithmetical scenario Alba were looking for when they stood on the list in 2021, and it should give them some limited leverage with the government, albeit any informal deals will have to be done on the quiet given the antipathy between the SNP and Alba. And if by any chance the Greens are crazy enough and angry enough to try to force an early election, it will be entirely up to Ash Regan and Alba to decide whether that happens. Right now might not be the ideal moment for the early plebiscite election we all want, but that doesn't necessarily mean the ideal moment won't arrive before 2026.
Current state of the parties: