Quite a lot of my take on this has already been posted above.
Firstly, as
@dee says, the vote was only to discuss developing a spending cap - there will have been a proposed mechanism for this, but it will likely change / be clarified before it goes to any formal approval vote. There's a good chance that some clubs will have voted yes at this stage but may not be keen on the final mechanism, and likewise they may iron out some of the concerns of the clubs voting against.
The precise mechanism is unclear, but the suggestion is that spending (likely to mean player wages, agent fees and transfer spend (probably amortisation-based rather than cash)) would be capped at between 4 and 5 times the lowest team's TV revenue. Last year, Leeds got the lowest revenue at £112m, which puts the cap at between £448m and £560m. That's the opening proposition, it could well change, and I suspect it will go up, if anything. At the top end, a club complying with UEFA's 70% squad cost ratio, would have turnover of £800m. City's was £713m last year, so they would not have been constrained by these rules, assuming they complied with UEFA's.
As
@The Nomad says, this gives a lot of flexibility to clubs lower down the league, so the likes of Everton and Forest could spend with abandon and not be penalised. This is a great position for them to be in, because as we know, Everton are not remotely at risk of going bust, so the rules give them flexibility and achieve the aims of PSR. Oh wait, Everton ARE in danger of going bust. These rules are a load of shit. Never mind, I'm sure the football regulator will be OK with them and won't try to interfere.
There's also the issue of "other costs". Clubs could run up huge losses when you add in non-playing staff costs and overheads. These rules do not address control of those costs. The existing PSR, focusing on losses in total, does address those costs by including them in the target measure, whilst the UEFA cost ratio effectively includes leeway to accommodate them (since the UEFA target measure will ultimately be 70% of turnover for squad costs, it effectively allows for 30% of revenue to cover other costs).
The bigger clubs will need to comply with the UEFA measures anyway, so there's an argument that they shouldn't have an issue with the new rules. I think City's objection is the 115 charges, just being spiteful. United have historically had a financial edge based on their huge commercial revenue base (although they have lost ground on that in recent years, and not just to City's artificially inflated number). They are probably banking on getting into the same league as City via boosting on-field and media revenues by being good at footy again - bless! Chelsea know they're in a mess regardless of what rules are implemented and I have no idea what Villa's beef is - these rules would probably suit them.
But this appeals to smaller, ambitious clubs who are prepared to take risks, or who feel they may be more attractive M&A targets if their prospective owners know they won't be constrained in the way Newcastle currently are. So we should expect more nation-state takeovers, and proxy wars on the field every weekend.
But I also feel like the PL is defying the regulator to interfere so they can say they had a scheme that had broad approval and the government shot it down. Playing politics, basically.
The scheme is bullshit, and it will encourage a lot of the smaller clubs to take chances and risk their future, whilst barely impacting the bigger clubs who will have to follow the UEFA model anyway. And at the end of it all, the big risk is that the TV deal won't continue to out-perform inflation over the longer term. The smaller clubs probably figure that if that happens then they'll be able to argue for a more even distribution of TV money - so the bottom team's revenue goes up, and everyone else can spend a bit more (even though their revenues will have gone down, proportionately). I get how that would appeal to the clubs lower down the league, but it's purely hypothetical. And if everyone is free to spend willy nilly, economics means prices will go up for everyone, and in that situation, the ones who will suffer are the ones who choose to spend responsibly (e.g. the likes of Brighton, Brentford, Bournemouth). They shouldn't be voting for this.