They’ve made it pretty clear they’re going to use 1.12 data.
After careful consideration, we decided on Patch 1.12: Drums of War as our foundation, because it represents the most complete version of the classic experience. https://worldofwarcraft.com/en-us/news/21881587/dev-watercooler-world-of-warcraft-classic
Besides the 1.10 loot tables for relic items and some items being gated on vendors. It seems we’re getting 1.12. We’re getting 1.12 stats confirmed by the PVP post here:
Nearly every single update has said 1.12. Now whether they consider CRBGs part of the data or some outside “server linking feature” is beyond me. But there is a very good argument for it being in there because it was the main feature of 1.12.