As far as I remember Holy Fury free expansion was released after the CK3 was announced, and numerous patches were also released even after CK3 release. So they kept resolving issues with CK2 even after CK3 was released. This is an acceptable wind down period for all people who have already purchased the game, so that they get the value for the things they already paid for. This is just Paradox paying off the implicitly assumed technical debt to the customers who were buying that product for years while expecting continuous development.
Here the situation is different, EU IV is discontinued almost a year before EU V is announced.
False.
CK3 was announced on 2019-10-19. (
https://forum.paradoxplaza.com/forum/threads/an-heir-is-born.1261140/)
Holy Fury released almost a year prior on 2018-11-13.
There was 1 patch
the day of the announcement (Patch 3.3), which was primarily to add their Monarch's Journey feature alongside making CK2 free.
CK3 released on 9/1/2020. There was only 3.3.3.1, 3.3.4, 3.3.5, and 3.3.5.1 afterwards, and they aren't what you'd hope for.
3.3.3.1 - Made it possible to launch the game at all on MacOS Big Sur. Only change.
3.3.4 - Adding the subscription DLC feature for CK2 (not applicable to EU4).
3.3.5 - Adding small rewards for being a subscriber for CK2 DLC after so long of being an obsolete game. Which were just key art after 45 days, a Spotify playlist after 75, and a discount on Age of Wonders III.
3.3.5.1 - Just done so that the CK2->EU4 converter worked after 3.3.5 broke it.
This doesn't read like you've interpreted it.
If we want to focus on patches just after announcement but before release:
3.3 - Day of announcement patch. Monarch's Journey feature, game made free to play. Includes some bug fixes due to adding a new feature.
3.3.1 - Same as 3.3.5.1 but for 3.3.
3.3.2 - Fixed a security issue that would allow malware execution with how Lua libraries were loaded for mods. Very obviously an exception.
3.3.3 - Fixes for Linux regarding the 3.3 content. Another security issue patch.
Out of all of these, only 3.3 proper fits your bill, and likely partially because they were adding a promotional mechanic.
It does suck, the state things are being left in (especially if you are a MacOS or Linux player!), but it is not outside the norm, and I expected this from the moment WoC was announced due to Johan's previous statements about the remaining DLC, especially once it became later apparent that literally nobody from Tinto had a hand in the development of WoC's content besides a dev's mod turned into content, implying that almost nobody remains for EU4 at Tinto.