You do remember that you originally started this itch.io page to fund the development, right? You do remember that you initially started tis page and told people that by buying it on itch.io, they get early access to new features, right?
A copy/pasta of your own words even at the moment:
Get earlier development builds now here on itch (even earlier on SubscribeStar), or add to your wishlist on steam for more complete stable releases soon!
Saying "Not every update is worth playing, especially if it's content you want" doesn't apply here since the itch.io builds released are still broken/incomplete (barely in an Alpha stage). It's not even about content, but functionality at this point.
What you did is switching your business model from originally being "Development being funded via itch.io" to "Development being funded via subscription" as you know people do appreciate your work enough to pay a monthly fee (you have numbers related the number of sales on itch.io) for it and as you know that they wouldn't pay said monthly fee if you don't give them some monthly candies, hence you abandoned the "development builds" side of itch.io and turn it into basically a sub-Steam release.
As an independent developer myself who work with the same tools are you, I just can't agree with how you have handled this on itch.io.
In fact, you might not know about it, but there are laws in Canada, US and the UK (at least) which protect consumers from exactly what you have been doing, though you're still in the gray zone (but close of being out of time). You can't legally ask for payment for a promised product in development and then, later, offer an upgraded version of said product still in development onto any other platforms/markets/buyers without first equalizing both products equally toward your original payers from the first market/purchases.
I'll give you some tips based on your way of versioning your project:
v.X.0.0.a are released version, meaning that once it reach v.1.0.0, you have reached a stable final build. This is what you would call a "Steam release".
v.0.X.0.a are development versions, meaning they are steps where features or content are added or heavily modified. Any changes in those are supposed to be distributed on itch.io as per your own original promises. You could also release a pre-Release on Steam with this version, if you're confident (though Steam has specific rules, even since the fiasco of the Greenlight, regarding development time and they don't allow what you're currently doing with itch.io.)
v.0.0.X.a are fixes and minor modifications that may change some part of the game. It can also includes minor content addition like some festival content. For example, an additional option in a menu or new settings, etc.
v.0.0.0.a are minor fixes for oversight errors. For example, typos (mistakes in texts), or some other small corrections.
Remember that, on Patreon, you're at v.0.3.1.c (from the your Patreon news update) and, here you're still at 0.2.8.a and the 2 versions are quite different state of the same product. Your original promise on itch.io when you introduced the Patreon/SubscribeStar funding method was that itch.io would receive the same update as the Patreon/SubscribeStar, but 1 month later. v.0.3.1.c came out on July 18 2022. Even if you decided to completely change anything in the project, you're already not following your own promise on releases to your itch.io buyers.
Even if you're thinking "but I don't have that version of the game anymore", the builds files are still available. You got no legal ground on leaving your buyers from itch.io out of the loop like you did.