Private Browsing in Kaspersky blocks third-party tracking & data collection. People usually have this on to prevent unauthorized scripts on certain popular public sites.
Here's how you get to it.
Settings > Protection > Private Browsing (On)
You can operate the OSV app when Private Browsing is set to “on”, but you must first disable blocking for the OSV app page in order to gain access.
There is an icon at the upper right in my browser which looks like this:
To disable blocking, click the icon and click on the button at the bottom of the menu which reads “Do not block on this web site.” That will allow a user to retain the privacy protections on all other sites but enable access to OSV.