I'm testing https://demos.telerik.com/kendo-ui/notification/index with the NVDA screen reader.
1. Notifications are not announced by the screen reader, violating success Criterion 4.1.3.
2. Notifications are not accessible by keyboard.
3. The "close" button is not semantically a button.
4. The "close" button is not focusable by keyboard.
5. Auto-hiding notifications violate the 2.2 guideline (enough time). I can give my user an option to see notifications for a longer time, say 100 seconds instead of 10, but unable to close them by keyboard, they can end up with an overflow of messages.
6. The color contrasts are insufficient (4.26 for the red ones, only 2.73 for the green ones).
Notifications are listed on https://docs.telerik.com/kendo-ui/accessibility/section-508-wcag as AA-level compliant, and while I understand they're one of the hardest component to make accessible due to their asynchronous nature, the current implementation is closer to a bad practices example than a correct solution.