Almost all cities are having cuts of frequency because Frontier doesn't have enough aircraft to maintain the current frequency plus OKC, TUS, RSW, and ICT which Frontier recently announced.
All cities that are seeing decrease in frequency (except RNO) will be back to normal next year when Frontier gets some new Airbuses and when the A318s start coming in.
It's only a temporary reduction.
RNO for now will be down to 1x permanently though at least for now.
"Generosity is giving more than you can, and pride is taking less than you need." - Khalil Gibran