Very useful. Information should be free for all.

Alas it breaks login pages which use Cloudflare captcha!

I first thought that uBO and/or Privacy Badger are the culprit and disabled those, but then still could reliably reproduce the bug. Then I disabled *ALL* my extensions and enabled them one by one, meanwhile testing logging in. When I turned on Web Archives, login stopped working, I got an error message after entering my credentials and clicking the "I am a human" checkbox on the popup Cloudflare captcha.

Once I disabled Web Archives, login started to work again.

Mind you, this test was done with uBO and PB still being disabled.