Starting at https://authors.curseforge.com/forums there is a category for website support; it contains a sticky alert from Torhal (hi Torhal!) saying that the category is discontinued as part of the transition. The provided "new" link is to https://support.curse.com/ ...
...which doesn't work. "The page isn’t redirecting properly" is Firefox's take on things, but I don't know whether that's a crappy translation of an actual HTTP redirect error code, or just Mozilla developer overreach as is their wont.
At a guess, I tried adding "forge" into that domain. And https://support.curseforge.com does work, and gets redirected to the site-in-progress transition page at https://xarth.force.com/curseforge/s/ from which I arrived here. There's also a suggestion to tweet at Curseforge, which I might try during the posted monitored hours.