I have to agree with
@GrinningRuiner. You lost two sun taking you to four, but at the start of the turn there was 6 sun. Sun calculation was at the beginning of the round, just like you get the extras before any cards are played. This is an effect of losing after that calculation of what you've earned had been completed. If i earn 600 bucks and lose 200 at the roulette wheel, it still doesn't change that fact that i earned 600 bucks...
That's like saying If you spend a two cost card before playing them, their effect shouldn't activate either.
Now, that said, i also believe is working the way it should work, but the wording should be changed to reflect what it does. I.e. "resets the value of the sun earned this turn by -2"