Webcam Covers & Tinfoil Hats
There was a time when covering one's webcam with tape would get you admitted to the psychiatric ward. Now, the FBI director recommends it as the "sensible thing you should be doing". Mark Zuckerberg in 2016 was seen with his webcam (& microphone) covered.
All this comes on the heals of Edward Snowden's reminder of the ease that recording devices can be co-opted for surveillance. An ideal password protection strategy may involves a wool-knit sweater as seen below, though this may be impractical at times.
As crazy as the above picture may seem, Edward Snowden in CitizenFour was seen doing this when required to enter his passwords,
Some manufactures have started to build camera covers directly into their monitor's webcam.
I do think though, that Lenovo / ThinkVision has their lens cover backwards.
Red indicator light
The universal language in video & sound to indicate 'recording' has been a red light. This light on many electronics was a red bulb or LED. This is in part why the red 'Record' indictor on video cameras is a red dot. Red is used as the spectrum stands out on the retina in both dark and light conditions. There is a reason that signalling beacons and record lights are red.
A red indicator light has become synonymous with 'on' 'hot' 'live' 'active' 'recording'. This is a classic case of skeuomorphism - adopting real world design language in the creation of digital design. Your phone continues this old tradition to use this design language in the video recording module.
Lenovo, ThinkVision
The Lenovo ThinkVision monitors have chosen to use a red indicator light to indicate their camera is off / covered. This is backwards from standard user design language.
On their devices, when the webcam is covered - aka 'off' - a red light marking is seen.
The red indicator disappears when you remove the cover, and turn 'on' the camera.
It is a bit unnerving to have a red dot staring at you all the time. Perhaps Lenovo chose to design their monitors as a testament to George Orwell's 1984. A daily reminder of the existential threats posted by the surveillance state, and to encourage vigilance in peoples behaviour and action.
I suspect the reason a red dot ended up on their webcams when closed is someone suggested it would be a nice reference to the ThinkVision logo to use their small red dot as a design feature. If so, this is a classic case of unintended consequences.
I'm unsure if their tagline, "Different is better" applies here...
Links
Discussion on red indicator lights at UX StackExchange, https://ux.stackexchange.com/questions/41434/why-is-the-record-icon-always-round-and-usually-red