From your quote:
>access to the exact product version for when your 12 consecutive months subscription started.
(my emphasis)
As for the rest of the quote from Jetbrains:
>You will receive perpetual fallback licenses for every version you’ve paid 12 consecutive months for.
In a one year subscription, the only version you will have paid 12 consecutive months for is the version that existed at the beginning of the 12 months. If a new version was released with only three months left in your subscription. Then it's impossible to have "paid 12 consecutive months for" it when your subscription is up.
Here's a screenshot[0] I just took of my account. The subscription started about 6 weeks ago when 2022.3 was the latest version. Thus, as shown in the screenshot it's the version I have perpetual license to. Even though 2023.1 was just released two weeks ago (roughly three weeks into my subscription) [1].
It's all worded terribly (probably intentionally so) so I don't fault anyone for getting the wrong interpretation. The whole thing gives me a bad impression even I though I love JB otherwise.
[0] https://imgur.com/a/SSLPijk
[1] https://blog.jetbrains.com/webstorm/tag/webstorm-2023-1/