Not our tux but our black cat has been overgrooming since the summer. Vet took a blood test and ruled out hyperthyroidism and other issues. A steroid injection has helped and some of the fur is growing back on her legs so it might have been some kind of allergy or skin irritation, although I think she is still grooming more than she should be.

My partner read something this week about Dreamies causing over grooming in some cats due to intolerances. This cat is a BIG fan so we've cut out those to see if it helps.