A workaround is to disable the shield while you perform the login action.
For a permanent fix, id.atlassian.com needs to be added to the Whitelist of Referrer Headers in Brave.
It seems it's already there in GitHub: https://github.com/brave/referrer-whitelist/blob/master/data/ReferrerWhitelist.json
However, you may have to use a beta version or clone the repository with the latest whitelist for it to work for you.
In my case I found the file under:
/home/<username>/snap/brave/84/.config/BraveSoftware/Brave-Browser/<afa...al>/1.0.35/1/ReferrerWhitelist.json
But a simple find ~ -name ReferrerWhitelist.json
will throw the exact location for you.
Not sure where the file will be stored on a Windows or Mac client, though.
On a Mac, it should be almost identical to Linux. On Windows, the file is likely to show up under %LOCALAPPDATA%\BraveSoftware\
or %APPDATA%\BraveSoftware\
.