I set up a private test repository, and tried to clone as follows:
git clone https://aryehw@github.com/aryehw/testPrivate
Cloning into 'testPrivate'...
Password for 'https://aryehw@github.com':
remote: Invalid username or password.
fatal: Authentication failed for 'https://github.com/aryehw/testPrivate/'
I found the following discussion, and tried some of the proposed solutions. No joy.
git clone: Authentication failed for <URL>
OS: Ubuntu 20.04, POP-OS
This is the output of git version:
amw@pop-os:~/git$ git version
git version 2.25.1