The Dev notes say: "We’ve gotten feedback that changing resources between Ages can be frustrating. While we like that the world changes a little between Ages and makes you reevaluate the map..." Personally, I don't think the problem was that we had to reevaluate the map, as in different ideal locations for buildings. However, a new resource cutting off access to developing tiles in a major city? That was a whole different thing. Hey, king. See that spot between the mountains? They found clay there. No one using it now, but because it's there, you are forbidden from ever extending the city in that direction." THAT was a problem for me. But maybe the solution, rather than not changing up resources might be to allow a civ to destroy resources, perhaps for a cost?
#Resource changes between ages
drifting quarry
deft turtle
or another solution could be to not have resources block city development? (thematically it's not great though)
rough raptor
I also don't like that some tiles that had a resource in the previous age don't have any resource on them in the next age, as that can worsen the adjacencies of unique buildings.