Running Opera desktop version 74.0.3911.107 , and the last 3 days i notice that the filter options on youtube.com not working correctly. Apparently seems a javascript issue.
When you select an option and then you select again a new one appears both options appear selected. In the screenshot shared above , for example , on Sort By column both Relevance and Upload Date are selected, while this field accepts only one value.
Tested with other browsers and seems to display correctly. So i suppose this is an Opera issue.