In ROUVY, turning ERG mode off works slightly differently than in TrainerRoad. ROUVY does not currently feature a manual resistance slider for workouts.
When you switch ERG mode OFF during a workout:
Your trainer automatically defaults to simulating a steady 1% slope.
You adjust your resistance and power output manually by shifting gears on your bike and changing your cadence, rather than moving an in-app resistance slider.
This is not nice because you are forced to a specific ring/cog combination depending on power and preferred cadence, and you might run out of gears.
Rouvy suggests to use virtual gears as alternative.