I'd been successfully using this for years, but some unknown time ago, the plugin's auth stopped working for me (possibly after a fresh install).

• if I create a ~/.gist-vim file containing token XXXXX, I get Post failed: (with no error message after the colon)
• if I do let g:gist_token = "XXXXX" (XXXXX being identical), everything does work as expected

The password flow doesn't trigger for me at all, even after reinstalling and deleting ~/.gist-vim

~/.gist-vim file has all the permissions I could give it. On macOS Big Sur.