I think the question here is: what is your source for how things "should" be?
That xp curve looks right to me from everything I've read and the in-era xp calculator supports it.
Here's a newsgroup thread from 2001 with raw xp numbers that agree with (probably because they reference, actually) the stratics xp calculator.
https://groups.google.com/g/alt.game...m/FdNJncznVJQJ
Now, if xp is different between Green and Blue, and Green works this way, then Green is right and I'd say something is wrong with Blue.