I wonder if some distro repos will stop installing mariadb instead of mysql whenever you try to install mysql. Always struck me as a weird thing to do since mysql never stopped development. (MariaDB.org seems to be still active, but there is now much more uncertainty (imo) compared to the mysql project)
At a glance, it seems like the open source MariaDB is just fine. It's the commercial company that is dead/dying. This may affect future development on the OSS side, but for now it seems like there's no immediate danger. As for why it's included over MySQL, it's undoubtedly the fact that MySQL has been owned by Oracle since 2010. Oracle has not been the most friendly to OSS communities in the past.
This is supposed to be about "racism, sexism" and stuff like that, but I don't necessarily see any contradiction. Because it's not unheard of that in troubled companies, questionable people rise to or stay in power that would not stand a chance in a more healthy environment where better candidates don't run away. Selection for the kind of person who'd rather be captain on a sinking wreck than some lower officer on a well run boat and I'd be surprised if there wasn't considerable correlation between those and the scandal that's supposedly the root cause here.