It will be released with Safari 26 (what is still in Beta) when the final version of Tahoe is released. I can't say if other features are added. In the Sequoia 15.7 RCs there is nothing new if you don't install the Safari 26 Beta update. At least I haven't found anything.
RC3 was probably the security update, released two days earlier. But there must be any bug fixes in the first two ones or maybe it got just prepared for Safari 26. There are no release notes. Also no firmware files in the Developer downloads.
My three updates were all just called 15.7, I only remember the last one was much smaller and included security fixes in the text. No word about RC in any update .I thought it was already the final version.
I saw it later in an article here but only for 15.7 RC1 and 2, there was no word about a Sonoma 14.8 RC and 15.7 RC3 was also not mentioned when it got released only the first and second one.
Sequoia is the recent version and they only wrote about the new Tahoe Beta as if 14.8 and 15.7 don't exist. There were also Ventura Betas or RCs released together with the first two 14.8 and 15.7 RCs.
The articles about the first two RCs of 15.7 were only copy and paste, it was a standard text mentioning release notes that don't exist. Very bad journalism here.
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