Honestly, AST has to work a lot harder to heal dungeons compared to the other two healers. I’m now leveling WHM, and I spend more time Holying than anything else (so basically like it was in SB, except now my GCDs are Solace > Cure II once my oGCDs are burned). Leveling AST, and I had to use more GCD heals compared to the other two because it felt as if the job just couldn’t keep up with the damage. COpp losing its stun also didn’t help, because I used it in the past to give a brief respite during the larger pulls for the tank (and to allow for some LS+Gravity spamming). COpp’s regen is weak for its CD, and CU barely warrants hotbar space at this point when you compare it to Sacred Soil and Asylum.
Lightspeed is also now saved (optimally) for Divination/Sleeve Draw windows, meaning that you can no longer use it for periods of heavy movement, MP conservation, or when you really need to get those heals off fast, which removes a lot of the versatility from the skill. Not using it during a Divination window means that you end up hurting your party members by being unable to throw out enough buffs during the time period due to having to double weave Draw and Minor Arcana between GCDs to Play Lords/Ladies while Divination is active.
There was also no real need to up Synastry’s cooldown from 90s to 120s. It does literally the same thing, and while good in dungeons, was pretty niche in some of the high-end content since you want to optimize around not using as many GCD heals (and it doesn’t benefit from oGCDs).
Horoscope should also function like WHM’s Plenary Indulgence, where a single GCD heal can proc the heal. While I watched a review on ShB AST that says it is good to top off tanks during pulls because of its short CD (and I agree and see the usefulness there), it also comes with overhealing the rest of the party more times than not (from my experiences). Overall, though, it feels less smooth to use compared to WHM’s Plenary, and I’m not terribly fond that I have to weave in a second Horoscope press to activate a 400 potency heal.