Using "power matching" features available in some apps is not recommended, as they can cause commands from the app to lag. Whereas your trainer updates its target position based on current readings several hundred times a second, power matching features only update targets every couple seconds, leading to inferior ERG tracking.
Fliiiiight has highly accurate power reporting (+/-1%), and we recommend using it as you source of truth. However, if you wish to match another powermeter for consistency between your indoor and outdoor rides you can learn how to do so here.
For assistance troubleshooting power readings, see Troubleshooting Power.