Word is getting reminders for accessibility before making a PDF.
When Word makes a PDF version of a document, it includes accessibility tags. These tags help screen readers (spoken for blind and the visually impaired) and also adjusting the PDF for small and large displays.
When saving a PDF (File | Export or File | Save a Copy) there’s a reminder to check accessibility before making the PDF version.
Clicking ‘Investigate Accessibility’ opens the Accessibility Checker pane alongside the documents.
This change is a reminder to be aware of accessibility issues before making a PDF. There does not appear to be any change to Word’s PDF conversion features.
After fixing accessibility issues, Word will be able to add more and better accessibility tags into the exported PDF.
Turn on / off
These warnings appear after selecting “Keep accessibility checker running while I work” on the Accessibility Checker pane.
The same option is at File | Options | Ease of Access
This is available in Word 365 for Windows Insiders v 1908 (Build 11916.20000)