Blizzard said they do not plan to extend the Winds of Wisdom 50% XP buff until Dragonflight pre-patch.

The community wanted the XP buff to be extended until Dragonflight launch. Unfortunately, that’s not happening. Previously, the same buff was extended until the Shadowlands pre-patch.

(Source)

Thank you for this feedback. We selected the timing of this buff to specifically benefit players who were preparing for Season 4.

We’re always thinking about when might be the right time to do an XP buff again in the future, and we do not have any immediate plans to announce at this time, but we’ll take this feedback into account when considering future leveling bonus events.