How can I report about the bug without joining SourceForge? I will not agree with the SourceForge Terms of Service.
The SourceForge version of the website is not maintained anymore. The project has moved to GitHUB. The developer has created a page with Bugs. You can join the discussion using the following link: https://github.com/spyder-ide/spyder/issues
There is no other way of reporting bugs since this one is the official one.