Blizzard has stated that the Damage Bonuses granted by main stat, newly added in Diablo 4 Season 5, will be reverted in Season 6 back to former values.
In their newly released Patch 2.0.1/2.0.2 Patch Notes, Blizzard included a line mentioning the previously buffed Main Stat bonuses would be reduced to prior values. This, in turn, will undo many of the changes that players were just getting used to in Season 5.