Most of it is in the podcast they just released.
This is aggrends twitter post.
“eposting myself is kinda weird but one thing I did want to make sure I mentioned that did NOT get mentioned in the podcast is that we are also fixing a bug with XP in dungeons. In previous beta builds, the XP earned per kill was awarded based on the highest level person in the group. If you are running, say, deadmines with 4 level 20s and 1 level 25, the amount of XP you get is extremely low per kill. With this fix, you should now receive XP based on your level relative to the mob as intended. This, combined with the 20% increase to base kills in dungeons should make it feel better and more even. XP gain is not going to be what it was in era, but it should feel significantly better now. We understand that some of you want to dungeon cleave to 60, but this is another one of those things that has to pass muster with our core pillars. That playstyle being the optimal way to level does not pass that muster and we need to hold firm on these balance adjustments. As it stands now after the adjustments, with perfect xp/hr play, the leveling rates in dungeons will be very close, if not equal to the speed you can level with optimal questing play. That’s how much better it was to level in dungeons in Era. Maintaining that balance is vital to our “World is the Main Character” and “Nurture and Protect Social Experiences” pillars together. Once the scales tip and dungeons become the clear winner, it has a cascading effect on player behavior and we have to consider that impact holistically.”