So it's quite confusing and I don't know how easy/hard this is to improve the situation, it mostly looks like this is an unintended side-effect of our release process + towncrier setup. Since this is a 2-week transition period, nobody has yet found the time to figure out what possible improvements we could do.

Previously mentioned in #32807 and #31469 (comment) and probably other places.

Let's try to summarize the issues:

• the changelog is not easily findable on the website. stable or dev website "ongoing development scikit-learn changelog 1.8" (bottom left) both point to https://scikit-learn.org/dev/whats_new/v1.8.html#version-1-8-0 which is empty. This is probably the easiest thing for now: copy the 1.8 changelog from 1.8.X branch to main so that the 1.8 changelog is correct on the dev website.
• towncrier setup: during the rc -> final period, we still have the fragments in doc/whats_new/upcoming changes in both main and 1.8.X. For the final, we generate the changelog with towncrier (without --keep), which removes the fragments. Then we forward-port this change in main. IIRC this was taken from another project, for example astropy does that as well.
• slightly annoying but less crucial: during the transition period, the 1.9 changelog on dev website has all the changes that will go in 1.8 plus some that will go in 1.9

cc @jeremiedbb in case you remember if you put more info about the situation somewhere.