Before re-fixing the TMY2 (ie, with magenta cast), Dmin = 0.40.
After re-fixing, Dmin = 0.26, which is typical of this film.
That's a drop of 0.14. Visually, I'd say the removal of the dye can explain this entire drop.
@Michael: There's no problem about discussing inclusion of B+F in graphs. I just didn't want my question about slope-change to be forgotten.