Are you using Opacity in Aprons ? If yes, check my post here about Opacity must be > 128 on Aprons made for 2020, otherwise grass will show up.
https://devsupport.flightsimulator.com/t/apron-opacity-threshold/10965?u=umberto67
I was waiting for a reply to know if this is the intended behavior (requiring to change opacity to always be at least 128 on all Apron of all sceneries we made and submitted them all again to the Marketplace) or it’s supposed to be fixed.