See my prior post on this matter, which prompted this controlled test: Autofocus Accuracy: Fujifilm GFX100S + Fujifilm GF 35-70mm f/4.5-5.6.
Confirming the results shown with the Fujifilm GF 35-70mm f/4.5-5.6, this page does the same assessment with the Fujifilm GF 50mm f/3.5. Using two GFX100 camera bodies.
Includes 34 frames plus frames from two cameras plus manual-focus reference frames, discussion, along with troubleshooting and mitigation advice.
Very interesting to me is that shooting outdoors today, I observed the variance firsthan and in real time in magnified Live View, using the procedure I outline.