Blizzard has pushed a new encrypted build for World of Warcraft Classic on the Developer Branch, Patch 1.15.0.49224. This was also spotted by MrGM on Twitter and can be seen listed on wow.tools.
Hardcore? Season of Mastery 2? Classic Plus?
The Developer Branch is encrypted and can’t be datamined, so we aren’t able to see what this patch has in store, but many Classic players are very excited.