World of Warcraft is changing how the auction house works to benefit smaller servers

pcgamer.com:

World of Warcraft's auction house will go region-wide for commodities in the 9.2.7 update. Blizzard posted the update on the official forums(opens in new tab), stating that the system is currently being tested on the PTR (Public Test Realm). A new chat channel will also be added for advertising services.

As it stands right now, each server has its own economy, so you'll find auction house prices fluctuate massively between busier servers and those that are less populated. Prices tend to be much higher on smaller realms because there are fewer players farming and crafting overall, and far less demand. 

The coming change means that commodity listings will become region-wide, so if you're struggling to keep up with the cost of flasks, pots, herbs, and other consumables for raids or mythic+, this should help even things out. 

You won't notice a difference in the auction house UI either and everything will appear to function as it does now. Aside from commodities, everything else on the auction house (such as armor) will remain server-specific.

Also announced for the 9.2.7 update is a new trade chat channel, specifically for advertising services like boosts.

Trade chat has become well-known over the years though it seems to be rarely used for its intended purpose. The channel spans every capital city in Azeroth (and elsewhere) so it's a place you'd usually see random chatter or guild recruitment, rather than players buying or selling stuff—though there is some of that as well.

But if you've spent any time in World of Warcraft in recent years, you'll have noticed that trade chat has become flooded with players advertising boosts for dungeons and raids. It's fine if that's what you're looking for, but it makes the channel