1 Demon Slayer: Kimetsu no Yaiba – Unwavering Resolve(Arc (aka Season 1)
2 Demon Slayer: Kimetsu no Yaiba – Mugen Train Arc (aka Season 2)
3 Demon Slayer: Kimetsu no Yaiba – Entertainment District Arc (aka season 3)
4 Demon Slayer: Kimetsu no Yaiba – Swordsmith Village Arc (aka season 4)
Am I wrong
I have proof That the 'Mugen Train' arc is seven episodes long (aka season 2) and is then followed by 11 wholly original episodes in the 'Entertainment District' arc (season 3)
Mugen Train is not an arc and was aired as in an episodic form and in a filmatic form,meaning it is not Season 2 if it was,they would not make a movie version of it