Well, this may turn into more of an issue this Fall… by default the new Safari browsers in iOS and MacOS will favor more privacy by default and seek to limit tacking across sites (by Cookies - in essence almost incognito mode all the time). If what you say is true, then I suspect there will be a direct rise in reCaptcha, especially on Apple devices running the latest system. I know I am 100% for receiving a picture reCaptcha when I have to click “I am not a robot.”
When looking at the statistics, can they break them out or tease the data by browser or iOS type to see if the info is more telling?
