[Origin Nightly] Twitch.tv blocks login with "browser not supported" error

Platform: Windows

Description

When attempting to log in to Twitch.tv using Brave Origin Nightly, the login modal displays the following error:

“Your browser is not currently supported. Use a recommended browser or read more here.”

The login form renders and credentials can be entered, but the error banner persists and login is blocked.

Hi! Thanks for reporting. We’ve seen an uptick in Twitch login issues affecting all browser versions, not just Origin.

We’re tracking those recent reports and working to resolve the issue. https://github.com/brave/brave-browser/issues/48861

Please try clearing your cookies/cache in full and/or trying to access via a Private Window. Let me know if you have any questions. Thanks!

The easiest way to work around this issue at the moment:

Delete all data related to Twitch that you can find here:
brave://settings/content/all

Restart Brave.

Go to https://www.twitch.tv/ and temporarily disable Brave Shields.

Log in, then re-enable Brave Shields.