Hi there,
Thank you for contacting pdf.js express forums,
The network request to pi.pdfjs.express/events is for telemetry purposes, see this post here:
What does the call to "https://pi.pdfjs.express/events" means? - #3 by system
This should not impact the browser’s functionality but it is likely one of your extensions is blocking the telemetry data.
Best regards,
Kevin Kim