These two parts of the announcement seem to contradict one another. The first part states that Whonix 17 be deprecated on 2026-02-06, but the second part states that Whonix 17 will be supported on Qubes 4.2 until Qubes 4.2 reaches EOL, which is currently scheduled for 2026-06-21 (six months after the release of Qubes 4.3, per the standard Qubes release support policy).
This is causing Qubes 4.2 users to become confused, because they mistakenly interpret this announcement to mean that they can’t continue to use Whonix 17 on Qubes 4.2, but when they investigate what they can do, they learn that Whonix 18 isn’t available on Qubes 4.2, so they infer that their only option is to upgrade to Qubes 4.3:
(CC: @marmarek)