I agree—there will be more information about the upcoming support deadlines for these platforms coming out soon, including an article on our support portal. In the meantime I’ve just edited the release post to provide more context, but the longer version is:
Microsoft ended support for Windows 7, 8 and 8.1 in January of 2023, and Apple typically provides support for the previous three versions of macOS. In turn, Mozilla moved support for these versions to the Extended Support Release (ESR) version of Firefox last year.
Tor Browser 13 is currently based on Firefox ESR 115, which will be the final ESR to support these platforms. This means we will no longer be able to support these platforms after we update Tor Browser to ESR 128 around Q4 this year.
Your next question may be: given that there are still Tor Browser users relying on these platforms, can’t the Tor Project support these platforms unilaterally? The short answer is no, but for a more in-depth discussion please see this thread about Windows specifically:
Ultimately, the same rational applies to macOS too.