You can try that, but there might be a few other things you can more easily try first.
Does the issue occur if you create a new profile and try it in that profile? (Make sure your original profile does not have any open windows; only the new profile should be open.)
Also, some other threads (references below) seem to indicate that clearing cookies for the site, or perhaps more thoroughly, using ‘Reset settings,’ might solve the issue. Seems this has affected some random folks.
There’s quite a bit here but peruse if you like:
- Problems with twitch on Brave - #23 by StrawberryStraw
- https://www.reddit.com/r/Twitch/comments/xm7how/something_went_wrong_when_trying_to_log_into/
- Twitch.tv Log in getting blocked on Brave - #58 by alexluc
- https://www.reddit.com/r/brave_browser/comments/xm9obp/brave_has_issues_with_twitch_for_some_reason/
- https://github.com/brave/brave-browser/issues/25598
Based on a quick read thru some of those it looks like you have good odds of getting past it if you ‘Reset settings.’