SonarQube 9.9.9 was only released for Enterprise and Data Center Edition, as it fixed a bug only relevant to large instances working with support through their upgrade migrations.
SonarQube 9.9 LTA is supported via commercial support until 6 months after the release of a new LTA (which happend in January, so that’s July 2025). But as far as the Community Edition is concerned, it’s essentially EOL already. 
You should upgrade ASAP.