Hi Remi.
Thank you for reaching out. It’s ok to do it here if it’s comfortable for you.
As a developer myself, I think it would be much better to inform about API changes in some other way before making them? By some email to API users or something. But I do realize you personally is not the one who made this change without prior notice, so please don’t take it personally, just take it as a random rant from someone who had to reply to numerous users complaints regarding this issue. Also, I think it’s a good thing to call “url” parameter how it’s actually called, not “referrer” or something else. And also display corresponding error message. Hey, just another random rant, sorry 🙂
To answer your question why the “url” parameter is used, I’m pretty sure I found an example with it on Stripe website. I cannot find it again, I assume it was removed from documentation not long ago. But, as you might understand, I haven’t seen it in a dream and decided to put it in the code 😉
Since there is no reason to use it anymore, it will be removed from plugin code in the next release.
Thank you once again for your time and effort. And sorry in advance for any offence as none meant. Just ranting. Can a man rant once in a while? 😉