I use many addons and extensions in my browsers some of it is for ad blocking, taking screen shots and VPNs. This question came to my mind while using free VPN addons. I usually uses VPN addons for watching videos which are IP blocked but switch offs ( in the image down right side on/off toggle button ) while using banking transactions, emailing and other personal and secure tasks.
I know that while switching on VPN; those companies monitor our browsing history and possibly save it in some databases. If we switch off our VPN will it still log our browsing history and send it to their databases. Can other installed add ons see/send user browsing history without their consent? Is their a add on/ extension which can monitor the behaviour of other add ons similar to firewalls in desktops?