Blizzard has posted upcoming Shadowlands PvP Tuning for April 26th which includes a nerf for the Assassination Rogue Tier Set.
BlizzardMage
FireBlazing Barrier’s absorb is reduced by 25% when engaged in combat with enemy players. This change also affects Blazing Barrier cast by Arcane and Frost’s Triune Ward runecarving power.Monk
MistweaverLife Cocoon’s absorb increased by 33% when engaged in combat with enemy players.Paladin
The effectiveness of Pure Concentration (conduit) has been reduced by 50% when engaged in combat with enemy players. HolyDivine Favor (PvP Talent) now increases the healing of Flash of Light or Holy Light by 40% (was 50%). Holy Light now heals for an additional 40% when engaged in combat with enemy players (was 20%). Flash of Light now heals for an additional 25% when engaged om combat with enemy players (was 15%). Retribution and Protection Flash of Light unchanged.Priest
HolyHabiliments of the Empyrean 2-piece set bonus now increases the cooldown reduction of your next Holy-Word-affecting spell by 10 seconds when engaged in combat with enemy players (was 15 seconds). Miracle Worker (PvP Talent) now reduces the cooldown of Holy Word: Serenity by 10% (was 20%).Rogue
AssassinationSoulblade Shadowhide 4-piece set bonus now causes your Poisons and Bleeds to expire 50% faster when engaged in combat with enemy players (was 100%).Shaman
RestorationHealing Surge now heals for an additional 25% when engaged in combat with enemy players, up from 15%. Enhancement and Elemental healing unchanged. Healing Wave now heals for an additional 30% when engaged in combat with enemy players (was 10%). Theurgic Starspeaker’s Regalia 4-piece set bonus now casts a Chain Heal at 70% effectiveness when engaged in Read more on wowhead.com