not to do 100% with cams, but the drain on the mobi may well be YOUR data being followed 24 hours a day! AKA the cookie/ads being trolled by Google FaceSlap and uncle Tom Cobly there is a simple way to cure it GET DuckDuckGo app ensure the cookie/ad stopping is running, last week I had 14,763 attempts BLOCKED by duckduck!I deleted the Nextbase app from my phone as it was drawing too much power when not even in use. It had used up 7% of my battery on one day when I hadn't used it. Now deleted. Sent an email to Nextbase stating the issues and I'll probably go for a refund as I bought the rear camera direct from them. The download time and refresh times of the clips via the app was painful too. Not a good experience all round.
(OH I stopped Chrome accessing the net, & deleted FaceSlap 4 years ago! BUT its still looking!) So there's a BIG drain and it may also be the CAM being searched?
duckduckgo also gives a weekly report of culprits!