I think it would be extremely useful if we could make profession screen to always go back to previously selected expansion filter. I'm leveling Kul Tiran engi right now and it's so
Leveling Mining from 1-300 - WoW Classic Guide
Making Gold With Early Professions - WoW Classic - Bitt's Guides
How to find a profession trainer (World of Warcraft) - YouTube
Class Trainer Plus
Silvermoon City Profession Trainer Locations in WoW Burning Crusade Classic - Wowhead