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
GitLab used to be awesome when it was the place to go after MS bought out GitHub. They had premium access for all public projects under a FOSS license and top-tier CI. Then as time went on, they began pulling support for various functions in a very Microsoftian EEE sort of way. First requiring credit cards fir new users to access the CI, then taking away the CI almost entirely except for a practically useless monthly allotment, then taking away the premium access for public FOSS licensed projects. If I were migrating today I would not have chosen GitLab, but it is where I settled after leaving GitHub and my projects have grown to depend on GitLab CI even if I’m now forced to run my own runners due to the extreme nerfs they’ve done to the hosted CI. I mirrored OpenRGB to Codeberg, but since the CI pipelines depend on GitLab I don’t see Codeberg becoming the main hub anytime soon unless they can execute GL CI configs. Sad to see how far GitLab has fallen though, it is unrecognizable from what it used to be as far as support for FOSS prohects goes, especially given how GitLab itself started as a FOSS project.