Fortitude/Colossus upgrade puts you at Less Current HP%

[duplexdsi]

If you already have Extra Health, buying Fortitude or Colossus (from full HP) will put you at less current HP percentage than where you started, unlike when just buying the items outright. Buying and selling multiple times can repeatedly cause this effect until you're red HP.

I haven't tested every health granting item, I just noticed this one so far