I'm one of the developers of the website https://www.tootukassa.ee. Suddenly we have received quite a lot of complaints about customers being unable to use our website with Microsoft Edge because they get an error message: "You’ve stumbled upon some vintage web tech". The reason seems to be that the website is added to Microsoft Cloud CV List (reason code 3). Message disappears and website turns fully functional after unchecking "Use Microsoft Compatibility List" flag from MS Edge Developer settings. Unfortunately this is not a satisfying solution for our customers!
It is very hard to determine reason why the page is added to CV list and what to do to get removed from the list - especially when the message does not disappear instantaneously while making some code improvements.
Our website is using jQuery and jQuery UI which are using some deprecated browser sniffing methods likenavigator.userAgent. Can this be the root cause of incompatibility? Or has anybody got any idea of what could be the cause?