I had the same problem. The fix is to add a query parameter before the page anchor:

document.pdf?t=123456#page=10

Edge caches PDF positions by the base URL. Adding ?t=${Date.now()} makes each link unique, so Edge treats them as different resources and doesn't use the cached page position.

Important: The query parameter must come before the #page= anchor, not after it.

// Example implementation  
const url = `${pdfUrl}?t=${Date.now()}#page=${pageNumber}`;  
window.open(url, '_blank');

This workaround was mentioned in What can I do to change this Edge PDF frame behaviour without JavaScript (Firefox works OK)