It would be more likely the Metal plate behind that holds the sensor to the ring this is the problem you cant buy the back plate officially you need to buy the stub axel with the plate fitted. There is a seller on eBay selling the back plate from Poland or somewhere like that but check with Renault Parts Direct with this info it's best to give them a chance as they are an official site trader/supplier. Its job is to maintain the gap but if it is the same as the other side then more likely the sensor attached is fowled up or broken. I had a rear sensor go down on my 172 the braking I think the system goes 50/50 front to rear or deactivates the ABS but it can be a handful. If the discs have been changed the bearing needs to be in the right place for the gap as well and if you get any parts find the genuine part number first then cross reference never take a part at it's description you more than likely wind up with a part that's for a standard Clio and wrong for yours. I'm not familiar with the magnetic rings but my experience with the castle style abs rings was that if the car detected more teeth than expected it thought the back wheels were going faster or slower than the front wheels an automatic ABS warning would happen.
View attachment 137884
View attachment 137885