The only exception is BFA’s daughter of ten lands XP potion that will remain.
the [Draught of Ten Lands] will still provide the 10% XP bonus, but will be capped at level 50. No other XP bonus potion will remain — the Elixir of Ancient Knowledge, Elixir of the Rapid Mind, and Excess Potion of Accelerated Learning will become poor quality and unusable. In addition, the Monk daily quest that grants you [Enlightenment] XP buff will still grant a buff, but instead of bonus XP, it will grant extra rested time. This is still functionally an XP buff, since you gain twice as much XP when rested, but it means you can’t just stack XP buffs on top of each other
https://blizzardwatch.com/2020/08/05/heirlooms-wow-shadowlands/