I have the same question. And It's not only about the last update, it's also about this mod. As soon as you get it and activate, all your old seeds stop working. I used to play one map I loved so much and one day I decided to make a few changes. I didn't succeed using map's seed in World Builder because it generates something similar to that map, but different in goody huts, resources etc. (I think the reason is you are not able to put gameseed in, only map) I realized I needed to extract a map from a savegame directly somehow. Then I found this mod. It is said It brings a new option "export map to log" which seems to be the solution. But it works only with newly started games. If you try to apply it to an old savegame the button doesn't show up. I also tried to start a new game using the seed of my favourite map, this mod and the previous version of game on which the seed works properly. But the map generated is completely different. So. The conclusion is this mod affects the map's seed no less than new update does. Does the mod's author know any way to extracr a map from a savegame and put it in a World Builder to customize? Thank you in advance.

Intended use of that option:
https://forums.civfanatics.com/threads/how-to-quickly-create-a-mod-from-a-civilization-6-map-using-zobtzlers-ynabmc-and-ynamp.637020/

I used that option, saved the game after loading the mod, exported and set everything there. I used the generated mod-map and set everything to import along with original starting positions. Map that the game loaded was still different

For me the button "Eport Map to log" doesn't show up anyway. It only shows up with the newly started games after getting mod activated. If the game was started before activating this mod there is no way to see the button and export map. Even though I activate the mod, load a game, save it with the mod activated, and load again. The button is not there.