I don't know. The article mentions in the abstract a "novel region-mapping (RegMap) SQL-based algorithm to perform genomic operations" and that "PostgreSQL extracts overlapping regions much faster than MySQL".

I don't have access to the article itself, so I cannot know what this novel algorithm is, what version of MariaDB was tested, and whether MariaDB was tested at all, as the abstract only mentions MySQL.

As far as GitLab is concerned, I didn't find where they mention this article. They generally recommend PostgreSQL over "MySQL/MariaDB" (for example here) because, apparently, GitLab is developed with the PostgreSQL in mind, all features and queries are optimized for PostgreSQL and don't work well elsewhere.