There is a hidden link to view the table on the Antivirus Events chart, that is marked as heading, but is not actually a heading for any section:
<h4><a href="#highcharts-data-table-0" tabindex="-1">View as data table.</a></h4>
1. Activate accessibility.
2. Open the /isc portal.
3. Select Metrics > Antivirus.
4. Inspect the "Antivirus Events" chart. Notice the link "View as data table" is marked as a heading.
This is expected behavior and by design in all current releases. The links and the data table are generated by the Highlights Accessibility library, the tags can not be modified and it is not possible to add the toggle to navigate between the table and the chart. Once accessibility is enabled for the user, the table is visible by default, however the link is hidden, so the user does not need to click on it.