Mongols - Improved Superior Mobility cost (25W 75G 100S) does not reduce to 100S (only cost stone) if you research the normal upgrade first

Age of Empires IV IV - Report a Bug
1

For Mongols, “Improved Superior Mobility” costs 25 Wood, 75 Gold, and 100 Stone. The normal “Superior Mobility” costs 25 Food and 75 Gold.

If you research “Superior Mobility” first, then the Improved version of the upgrade should only cost stone.

However, “Improved Superior Mobility” continues to cost 25 Wood, 75 Gold, and 100 Stone.

Image shows “Superior Mobility” researched, but the Improved version still costs Wood and Gold.

AoE4 Mongols Superior Mobility Improved Cost
AoE4 Mongols Superior Mobility Improved Cost822×299 257 KB

Build: 12.0.1974.0