Wrong variable name: performance_schema_max_prepared_statement_instances should be performance_schema_max_prepared_statements_instances

This is a documentation bug only; the server behaviour is correct.

The documentation spells the Performance Schema system variable as performance_schema_max_prepared_statement_instances (singular "statement"). The variable the server actually implements is performance_schema_max_prepared_statements_instances (plural "statements"), the same name MySQL uses.

The plural name has been used since the variable was added in MariaDB 10.5.2 (commit 7af733a5a2c, "perfschema compilation, test and misc fixes") and is unchanged through current releases. See sql/sys_vars.cc, Sys_pfs_max_prepared_stmt_instances. The server has no singular alias.