Hello there,
I think there is some kind of bug regarding farming gilding... It's only bugged when you have standard farming on the same level as bonus from gilding ( in my case I had 47 standard farming + 47 from gilding ) and I couldn't go higher than 47 ql of my plants. I've harvested flax for like 4-5 times and always 47 ql. My carrots & beetroots are varing from 47 to 43 ql for like 2 weeks or maybe more and can't get higher than that as well.