All we know is that the season end has been announced as per the pinned blue post:-
https://eu.forums.blizzard.com/en/wow/t/shadowlands-season-4-ending-soon/392882
In this announcement they covered the Dracthyr
The Winds of Wisdom 50% Experience Buff Now Live!!
If you’re just returning after a hiatus from World of Warcraft, leveling another character (or two), or preparing to get ready for the Dragonflight expansion then this is the perfect time to jump into the game. Beginning the week of October 4 with each region’s local weekly reset, all World of Warcraft* players level 10-59 will gain the experience buff called “Winds of Wisdom,” which will increase experience gains by 50%!
Don’t delay. The winds will shift once more when the new dracthyr Evoker becomes playable during the Dragonflight pre-expansion patch, and the experience buff will no longer be available.
** Experience boost not available in World of Warcraft Classic titles.*
https://worldofwarcraft.com/en-us/news/23859628/the-winds-of-wisdom-50-experience-buff-now-live
This would seem to indicate Dracthyr are only available to those who purchase DF:-
All new race & class, the Dracthyr Evoker (available at or before launch)
https://eu.shop.battle.net/en-us/product/world-of-warcraft-dragonflight
But not everyone will have access to the Dracthyr: it will only be available for those who have purchased the Dragonflight expansion.
https://blizzardwatch.com/2022/10/10/dragonflight-pre-patch-2/