You’re right — the “Core Ultra 285K” is technically Intel’s latest. Looking at Hardware Unboxed’s review of it, it’s actually a considerably worse performer than Intel’s prior 14900K. I suppose the lackluster performance is why I wasn’t aware Intel changed their branding.
There’s also some compatibility issues reported with the 285K — though I don’t know if those issues would affect Qubes or only gaming. The 285K being a year newer is something to consider regarding end-of-life timelines, however.