Each provides 15,000 XP per brew (which yields 3 potions).
Unlike today (2025+), Alchemy in 2021 had no "overflow XP" from minions that auto-brew. You had to stand at a brewing stand for hours. The key mechanics were: alchemy xp calculator hypixel skyblock 2021
16,172,425 ÷ 22.5 ≈ 718,775 potions