Problem/Motivation
PopperJS is deprecated in Drupal 9 as it was only used by Quickedit, a module that is not in Drupal 10:
#3307471: Deprecate popperjs
Proposed resolution
Remove PopperJS in Drupal 10
Remaining tasks
User interface changes
none
API changes
not sure yet.
Release notes snippet
The popperjs library was replaced with it's successor, floating-ui.