Interesting, sounds like LODO techniques! I was considering using 1/2 a Campden tablet in my water next time to try to purge chlorine, so maybe that'll have the same oxygen scavenging effect your Vitamin C has? Planning to make a Citra/Mosaic Hazy IPA in a few weeks so I'll definitely give this...
I believe my beers are all suffering the same thing yours are, but the flavor in mine is detectable after about 2 weeks in the keg as the initial hop aromas are declining (I mostly make hoppy styles). I wonder if you tasted this because of the high temps causing the yeast to make ethyl acetate...
You able to share the recipe or is it a trade secret!? I've made the Centennial Blonde and it was good but not exactly my favorite, looking to try a different light beer for visitors.
Are you using a refractometer to measure? Seems like a normal FG if you forgot to correct the reading. No insult intended if this not the issue, I learned the refractometer FG correction lesson after much confusion...