If you’re posting users information to a public repo, then you fully deserve whatever impacts you’ll face when you have to delete it.
Like their name and email address in every commit they submit?
I've already seen a notice from GitLab requiring me to consent to waive my rights to have that info deleted if, e.g. I were to contribute to the GitLab open source project. But I'm not sure that that's even enough for GDPR.