Password error message

Utilizing the Firefox extension, there are some sites like https://mail.protonmail.com on which I press the autofill button and the credentials autofill fine, but then when it automatically tries to log in, I get a message saying “Please enter your username and password”. I also get this message when I click on the Login button after the credentials are automatically filled in. If I delete the last character of the username or password and retype in that character, then it logs in with no issue. Let me know if I should submit this somewhere else, thanks!

Nextcloud Version: 14.0.3
PHP Version: 7.2.12
Passwords Version: 2018.12.0
Browser and Version: Firefox 64.0
Client OS and Version: Windows 10
Server OS and Version: FreeBSD 11.2-RELEASE

This is most likely because the website uses a framework like “Angular” for it’s login form instead of a classic html form with post. This may make it incapable of detecting the automatically filled values.
I will change the autofill to behave more “humanly” in the next bugfix version so it could fix this issue.