I’m not a healer main but healer balance seem to be struggling a bit more than dps and tanks right now and something I have heard a lot of people talking about recently.
Preservation evokers are doing way more throughput than other other healers even vs mistweavers and resto druids which should also be king of throughput. It would seem the logical solution to nerf them as they are way ahead of other healers but this late into a tier it might be easier to simply buff other healers as to not make content harder.
Many mythic raid team bring 2 preservation evokers on many fights and even manage to 3 heal on ovinax mythic because they’re doing massively more healing than other healers.
For M+ resto shamans seem the de-facto healer with close to 46% of the population already in +10 keys and over. With them bringing a very valuable interrupt and earth shield being one of the most valuable buff this season.