Website login issues with latest update

[rooroo]

Since one of the recent updates perhaps 3 updates ago I have not been able to logging to some websites.
For example deviantart.com no longer allows me to login it is showing me my password is incorrect
when it isn't. I have been in contact with deviantart helpdesk and they have known about an issue with
firefox preventing people from logging in.

At present the only way to login now is to perform password reset every time.

[siffemcon]

While on the login page, try clicking the padlock to the left of the address bar > Clear cookies and site data > refresh the tab.

[rooroo]

Hi,
I did try that, unfortunately it has no effect, and results is the same error as shown.

[rooroo]

And also while on the login page if the cookies are wiped it shows a timeout prompt.

[siffemcon]

Does that also happen in Troubleshoot mode (https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode)? If so:

Does that also happen with a clean new profile (https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles)?

If neither works, file a web compatibility issue:

- via the 'Report broken site' option (https://support.mozilla.org/en-US/kb/report-breakage-due-blocking) (Send technical and interaction data to Mozilla must be enabled)

- on webcompat.com (https://webcompat.com/issues/new), esp. if you want to include a screenshot), esp. if you want to include a screenshot

[rooroo]

unfortunately Firefox has no report broken site option in the menu shown on that page, if it is, it is hidden somewhere I can not find.
I'm not a github user no account for webcompat ...

[rooroo]

this is a frequently reoccurring issue with a lot of users. not just me.