WoW Classic’s 20th Anniversary servers have had a real issue with the Black Lotus crafting reagent in the late game. Often at an incredibly exorbitant price, repeated hotfixes aimed at fixing this have not led to any noticeable improvements. There are at least three hotfixes that come to mind, each doing something like adding a spawn timer to hopefully help with the price.
Though the price has gone down a bit — only at 90g on Dreamscythe Horde, it’s still incredibly high for everything that uses Black Lotus in WoW Classic. The prices can still fluctuate wildly, depending on faction/server/time of day. While we don’t know what Blizzard intends to do, they have vowed to continue working on the problem.
Blizzard plans on actively addressing the problem, which is a good idea. While yes, this is kind of market tampering, it certainly sounds like the right thing to do, to help players farm (or buy) Black Lotus without it costing an arm and a leg.
WoW Classic devs confirm they are working on a fix for the "Black Lotus" problem
In the last few months, WoW Classic players have given feedback and complaints about the continued high cost of Black Lotus on the 20th-anniversary servers. For those that aren’t familiar, it’s a late-game crafting reagent used in Alchemy, Enchanting, and Tailoring. While you won’t use it much, if at all, on the Cataclysm servers, you can make a 24-slot herb bag.

You also need 4 of them to make an Alchemist’s Stone, and 1 per any of the Flasks you can craft right now — Distilled Wisdom, Chromatic Resistance, Petrification, Supreme Power, and Titans Flasks. Some players just say that the content isn’t difficult but it's unnecessary, but not everyone agrees that ignoring the problem is the solution.
Adding more Black Lotus to the 20th Anniversary servers won’t fix it, we don’t think, nor will simply tampering with the spawn timers again. That will just increase the number of bots that are farming the reagent in-game.
We don’t know what solution Blizzard will come up with, but a solution from the Season of Mastery would be nice. The Black Lotus herb was updated in the older WoW Classic servers, where there was a small chance to also receive a Black Lotus when farming high-level herbs.
Blizzard said, through Community Manager Linxy, that they will provide an update as soon as there is more information on the solution they will be going with. Hopefully, the prices will come down. While no, you don’t need flasks to complete content, many guilds require them, and it’s also fun to simply hit much harder through buffs like a Flask of Supreme Power.