I have a brand new installation of XAMPP 7.4.19 on WIndows 10 Pro x64 20H2. I have been upgrading a friend’s WordPress site locally, and I have it working in WP 5.7.2.
The one remaining wackiness is that URLs for navigating between pages are broken. They have “localhost” in them twice. For example see https://i.imgur.com/PoDNE1v.png (if I insert it with img tags the right side gets cut off). The cursor is hovering over the “About <redacted>” menu button. Note in the HTML on the right the url associated with that button, “http://localhost/<redacted>/?page_id=2". But at the bottom left it shows where the button will actually take you; “http://localhost/localhost/<redacted>/?page_id=2" which of course doesn’t work.
The links attached to WordPress buttons work. For example, if I click the redacted blog name at the top left and pick “Dashboard”, it takes me to the dashboard.
I installed XAMPP manually from a zip file and don't remember doing anything to the configuration other than running setup_xampp.bat.