Blizzard outlined some Discipline Priest changes that will be applied via hotfixes to the Beta soon.

(Source)

Hello Priests!

Thank you for your feedback on our recent changes to Evangelism. Discipline healing scales faster than other healing specializations, as target count increases, which makes it challenging for us to tune the spec to be competitive in both small-scale and large-scale content.

To address this, we’re changing Sins of the Many to a low-level passive and increasing its effectiveness. Discipline is currently overperforming our tuning targets in raids in Dragonflight, so we’re doing this alongside several changes to decrease the specialization’s overall power.

You’ll see the following changes as hotfixes to the Dragonflight Beta over the coming days.

Discipline

Sins of the Many is now a passive learned at level 12.

Increases damage by 30% (was 12%).

Damage increase diminishes above 5 Atonement applications (was 1).

In the talent tree, Sins of the Many has been replaced with Blaze of Light.

Blaze of Light increases the damage of your Smite and Penance by 8%/15% and Penance increases or decreases your target’s movement speed by 25%/50% for 2 seconds.

Blaze of Light is no longer a PvP Talent.

Evangelism once again has a 1.5 minute cooldown (was 3 minutes).

Spell damage heals all targets affected by Atonement for 40% of damage done (was 50%).

Power Word: Radiance now applies Atonement for 60% of its normal duration (was 50%).

Schism increases spell damage to the target by 15% (was 25%).

Malicious Intent increases the duration of Schism by 6 seconds (was 3 seconds).

Harsh Discipline has been redesigned.

Every 10 / 5 casts of Smite, your next Penance is free and fires an additional 3 bolts. (Was: When Atonement has healed a total of 200 / 100 times, your next Penance is free and fires 3 additional bolts).

Please note: these changes will not be applied all together to the Dragonflight Beta. We expect to deploy them for testing separately over the next few days.

Thanks again for all of your feedback.