I don't currently use GitLab, but if I did I'd help them free up space by moving repositories elsewhere.
Some repositories might be dormant because they just work. Relatively small tools that do 1 thing very well may not see many issues, PRs, etc, but may have many users. Albeit, anything of moderate complexity will likely see bug reports and feature requests along the way. But it is possible for simpler tools to have large user base with little such requests.
In other cases, some repositories may be source code to replicate experiments from a journal article or conference paper. These won't change and shouldn't change once the article has been published. Such repositories are deliberately dormant but serve a purpose.
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
I don't currently use GitLab, but if I did I'd help them free up space by moving repositories elsewhere.
Some repositories might be dormant because they just work. Relatively small tools that do 1 thing very well may not see many issues, PRs, etc, but may have many users. Albeit, anything of moderate complexity will likely see bug reports and feature requests along the way. But it is possible for simpler tools to have large user base with little such requests.
In other cases, some repositories may be source code to replicate experiments from a journal article or conference paper. These won't change and shouldn't change once the article has been published. Such repositories are deliberately dormant but serve a purpose.