I have two laptops with built-in webcams. One is a Toshiba Satellite Pro C50-A-1E6 and the other is a Toshiba Satellite Pro P200 PSPB7E-02800TEN. Both machines run without any issues on what were clean installations of Windows 10 Pro x64 (now at feature update 1909). The appearance of the Blue Spot ONLY occurs with thse two devices. Other devices I operate use external USB connected webcams and are entirely free of Blue Spot.
Even if the webcam detection feature is an inessential, the evidence that it appears to be flawed is not reassuring. I have been assuming that since it appears able to detect built-in but not external webcams that the feature might already be built in to Avast Free but is not activated as it would be in Avast Premium. That being the case, I would say that it appears to be flawed.
This has been my rationale from the commencement of this topic.