As of July 14, 2022, all flavors of Ubuntu 21.10, including Ubuntu Studio 21.10, codenamed “Impish Indri”, have reached end-of-life (EOL). There will be no more updates of any kind, including security updates, for this release of Ubuntu.
If you have not already done so, please upgrade to Ubuntu Studio 22.04 LTS via the instructions provided here.
No single release of any operating system can be supported indefinitely, and Ubuntu Studio has no exception to this rule.
Regular Ubuntu releases, meaning those that are between the Long-Term Support releases, are supported for 9 months and users are expected to upgrade after every release with a 3-month buffer following each release.
Long-Term Support releases are identified by an even numbered year-of-release and a month-of-release of April (04). Hence, the most recent Long-Term Support release is 22.04 (YY.MM = 2022.April), and the next Long-Term Support release will be 24.04 (2024.April). LTS releases for official Ubuntu flavors (not Desktop or Server which are supported for five years) are three years, meaning LTS users are expected to upgrade after every LTS release with a one year buffer.