I ran the accessibility check using Chrome Developer tool. One of the issues reported was that -
[aria-*] attributes do not have valid values
This was for the tab element. The button has [aria-controls=“panel-12”] but the associated panel has the id of just “panel-”. The number 12 is not added to the id of it and hence the warning. Please see image below. Is it possible to add the number to the id as well?
Also, the [aria-labelledby] attribute corresponds to “tab-12” but no ID is assigned to the button for tab-12. This returns another warning in accessibility checks.