Comment # 26 on bug 1194193 from Takashi Tamura

I see the same issue.

In Browser Console of Firefox, I see the following error messages:

> Cookie ���������Bugzilla_login_request_cookie��������� does not have a proper ���������SameSite��������� attribute value. Soon, cookies without the ���������SameSite��������� attribute or with an invalid value will be treated as ���������Lax���������. This means that the cookie will no longer be sent in third-party contexts. If your application depends on this cookie being available in such contexts, please add the ���������SameSite=None��������� attribute to it. To know more about the ���������SameSite��������� attribute, read https://developer.mozilla.org/docs/Web/HTTP/Headers/Set-Cookie/SameSite
> Cookie ���������Bugzilla_login��������� does not have a proper ���������SameSite��������� attribute value. Soon, cookies without the ���������SameSite��������� attribute or with an invalid value will be treated as ���������Lax���������. This means that the cookie will no longer be sent in third-party contexts. If your application depends on this cookie being available in such contexts, please add the ���������SameSite=None��������� attribute to it. To know more about the ���������SameSite��������� attribute, read https://developer.mozilla.org/docs/Web/HTTP/Headers/Set-Cookie/SameSite
> Cookie ���������Bugzilla_logincookie��������� does not have a proper ���������SameSite��������� attribute value. Soon, cookies without the ���������SameSite��������� attribute or with an invalid value will be treated as ���������Lax���������. This means that the cookie will no longer be sent in third-party contexts. If your application depends on this cookie being available in such contexts, please add the ���������SameSite=None��������� attribute to it. To know more about the ���������SameSite��������� attribute, read https://developer.mozilla.org/docs/Web/HTTP/Headers/Set-Cookie/SameSite

Firefox 109.0.1
macOS 11.7.3

See also

https://hacks.mozilla.org/2020/08/changes-to-samesite-cookie-behavior/

I wish it would help.