If your IP (and possible your browser) looks “suspicious” or has been used by other users before, you need to add additional information for registration on gitlab.com, which includes your mobile phone number and possibly credit card information. Since it is not possible to contribute or even report issues on open source projects without doing so, I do not think any open source project should use this service until they change that.
Screenshot: https://i.ibb.co/XsfcfHf/gitlab.png
It’s disgusting.
It should be illegal to require any personal information unless you can prove that it’s literally impossible to provide your service without it, and always illegal to share that information with anyone (but a payment provider exclusively for verification purposes) for any reason.