Glass/plastic disc cover over lens droppng off

I have a RING floodlight cam pro. The camera and lights work fine - and the image is great but over the last few days the disc of glass/plastic keeps coming loose which means I dont get a clear image as the disc creates a problem. 1. Should that disc be fixed on - or is this something I should have removed when installing it 2. If it is integral and protects the lens itself how can I make it stay put ?? I don't want the lens to be damaged by the weather. thanks