Spayed half a year ago

Hello. From the skin features in the picture, your cat very likely has a fungal skin infection. You can try a Wood’s lamp for a quick check; if the lesion shows fluorescent green spots under the light, it’s basically confirmed as ringworm.

For ringworm, first shave the local area, fit an Elizabethan collar, then use terbinafine hydrochloride spray. If the Wood’s lamp shows nothing, go to a vet for a skin scraping to identify the pathogen and use targeted medication.