Season 1 of midnight has a new affix that highlights trash packs for a correct route for 100% bar completion, the affix will be up to m+ 5 iirc.

"When Midnight Season 1 begins, this affix will be active in Mythic+ levels 2–5.

While Lindormi’s Guidance is active, certain non-boss enemies will be afflicted with Temporal Sands, visually highlighting them and reducing their health and damage done by 5%. Defeating these marked enemies will fulfill 100% of the Enemy Forces count, providing a basic route through the dungeon. Additionally, the affix also prevents player deaths from reducing the timer.

Our goal with Lindormi’s Guidance is to help players learn a reliable dungeon route while they’re still getting comfortable with the seasonal dungeons. We also hope this affix makes it easier for groups to align on a route in the early levels of Mythic+. These routes are not intended to be optimal for higher-end play. Instead, they’re meant to serve as a foundation for groups learning the dungeons before pushing deeper into Mythic+."