NEWS FLASH
Spain’s national carrier Iberia will commence seasonal flights between Madrid and Ljubljana next summer. As previously reported, the airline applied for Slovenian state subsidies in return of commencing operations. The carrier will maintain two weekly flights between the Spanish and Slovenian capitals from July 29 until September 5, with the 100-seat CRJ1000 aircraft. It will provide 2.500 seats each way between the two next summer. The airline previously served Ljubljana for a short period during the summer of 2021. Further flight details can be found here. Tickets are now available for purchase through the airline's website.

Comments
My guess is that 1st option is more likely
Also 2022 saw Iberia operating A320s for the same period, now we'll have CRJ1Xs, so "maybe" the aircraft is meant to operate in winter months as well
B) Iberia flew to LJU in 2021 not 2022.
B. Fair enough, my bad
lun., 2 sep Logo AIR NOSTRUM
15:30 18:05
Ljubljana Joze Pucnik(LJU) - Madrid Adolfo Suarez-Barajas(MAD) T4
IB8667 . Canadair (Bombardier) Regional Jet 1000
Operado por AIR NOSTRUM
2h 35min.
Escala en Madrid Adolfo Suarez-Barajas MAD - Tiempo largo de conexión: 2h 45min.
Logo Iberia Express
20:50 22:45
Madrid Adolfo Suarez-Barajas(MAD) T4 - Tenerife Norte Los Rodeos(TFN)
IB3938 . Airbus A320 (Sharklets)
Operado por Iberia Express
Asegúrate el mejor precio
Básica
918€
Avios
Obtén un mínimo de 4.410 Avios
Equipaje de mano
Incluida 1 pieza hasta 10 kg (56x40x25cm).
2021: 2 weekly for one month with A320
2022: nothing
2023: nothing (despite Fraport saying they would be back)
2024: 2 weekly for one month with CRJ1000
2030: 1 weekly for two weeks with Cessna 172
They*
Average net loss of adria was 4.3