While using Firefox Multi-Account Containers, it is not possible to log on into Twitch.
The returned error message is always "Your browser is not currently supported.". Logging in on the same Firefox instance (ver. 108.0.1) without using a container for Twitch works. According to the web developer tools, there seems to be a problem with the Integrity service, especially a non-descriptive cloudfront error resulting in a 400 http error code.